Treatment of teeth by aligners

ABSTRACT

A method for treating a subject&#39;s teeth. A target configuration for the subject&#39;s teeth is determined. Receiving features are produced on a dental base in response to the target configuration, the receiving features being configured to receive physical tooth models. The physical tooth models are assembled on the dental base to form a physical arch model. A dental aligner is produced using the physical arch model to move the subject&#39;s teeth to the target configuration.

CROSS-REFERENCES TO RELATED INVENTIONS

This application is a continuation of U.S. patent application Ser. No.14/255,832 filed on Apr. 17, 2014, now U.S. Pat. No. 9,939,999 issuedApr. 10, 2018, which is a continuation of U.S. patent application Ser.No. 12/511,943 filed Jul. 29, 2009, now U.S. Pat. No. 8,740,614 issuedJun. 3, 2014, which is a divisional of U.S. patent application Ser. No.11/404,332, filed Apr. 13, 2006, now abandoned, claims the benefit ofU.S. Provisional Patent Application No. 60/676,278, filed on Apr. 29,2005, which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

This application generally relates to the field of dental care, and moreparticularly to the field of orthodontics.

BACKGROUND

Orthodontics is the practice of manipulating a subject's teeth toprovide better function and appearance. In general, brackets are bondedto a subject's teeth and coupled together with an arched wire. Thecombination of the brackets and wire provides a force on the teethcausing them to move. Once the teeth have moved to a desired locationand are held in place for a certain period of time, the body adapts boneand tissue to maintain the teeth in the desired location. A subject maybe fitted with a retainer to help keep the teeth in the desiredlocation.

Orthodontists initially base their treatment on a mental image of thesubject's physical orthodontic structure and a mental image of a desiredphysical orthodontic structure for the subject, which may be assisted byx-rays and/or models. Based on these mental images, the orthodontistrelies on his/her expertise to place the brackets and/or bands on theteeth and to manually bend (i.e., shape) wire, such that a force isasserted on the teeth to reposition them into the desired physicalorthodontic structure. As the teeth move towards the desired location,the orthodontist makes continual judgments as to the progress of thetreatment, the next step in the treatment (e.g., new bend in the wire,reposition or replace brackets, head gear, etc.), and the success of theprevious step.

In general, an orthodontist makes manual adjustments to the wire and/orreplaces or repositions brackets based on his or her expert opinion.Unfortunately, in the oral environment, it is difficult for a humanbeing to accurately develop a visual three-dimensional image of anorthodontic structure due to the limitations of human sight and thephysical structure of a human mouth. In addition, it is difficult (ifnot impossible) to accurately estimate three-dimensional wire bends(with accuracy within a few degrees) and to manually apply such bends toa wire. Further, it is difficult (or impossible) to determine an idealbracket location to achieve the desired orthodontic structure based onthe mental images. It is also extremely difficult to manually placebrackets in what is estimated to be the ideal location. Accordingly,orthodontic treatment is an iterative process requiring multiple wirechanges, with the success and speed of the process being dependent onthe orthodontist's motor skills and diagnostic expertise. As a result ofmultiple wire changes, cost and subject discomfort is increased. Thequality of care may also vary greatly from orthodontist to orthodontist,as does the time to treat a subject.

The practice of orthodontics relies heavily on the expert opinions andjudgments of the orthodontist. Many innovations have been developed toaid orthodontists and other medical professionals attempting to alignteeth. For example, U.S. Pat. No. 5,518,397 to Andreiko, et. al.provides a method of forming an orthodontic brace. The method includesobtaining a model of a subject's teeth and a prescription of desiredpositioning of the teeth. The contour of the subject's teeth isdetermined from the model. Calculations of the contour and the desiredpositioning of the subject's teeth are made and custom brackets are thencreated for receiving an arch wire to form an orthodontic brace system.The device of U.S. Pat. No. 5,518,397 places an arched wire on thebracket in a progressive curvature in a horizontal plane and asubstantially linear configuration in a vertical plane. The brackets arecustomized to provide three-dimensional movement of the teeth. U.S. Pat.No. 5,518,397 to Andreiko, et. al., and all of the patents andreferences referred to in this specification, are hereafter incorporatedby reference in their entirety.

Other innovations relating to bracket and bracket placements have alsobeen patented. For example, such patent innovations are disclosed inU.S. Pat. No. 5,618,716 entitled “Orthodontic Bracket and Ligature” (amethod of ligating arch wires to brackets), U.S. Pat. No. 5,011,405“Entitled Method for Determining Orthodontic Bracket Placement,” U.S.Pat. No. 5,395,238 entitled “Method of Forming Orthodontic Brace,” andU.S. Pat. No. 5,533,895 entitled “Orthodontic Appliance and GroupStandardize Brackets therefore and methods of making, assembling andusing appliance to straighten teeth.”

Kuroda et al. (1996) Am. J. Orthodontics 110:365-369 describes a methodfor laser scanning a plaster dental cast to produce a digital image ofthe cast. See also U.S. Pat. No. 5,605,459, and U.S. Pat. Nos.5,533,895; 5,474,448; 5,454,717; 5,447,432; 5,431,562; 5,395,238;5,368,478; and 5,139,419, assigned to Ormco Corporation, describingmethods for manipulating digital images of teeth for designingorthodontic appliances.

U.S. Pat. No. 5,011,405 describes a method for digitally imaging a toothand determining optimum bracket positioning for orthodontic treatment.Laser scanning of a molded tooth to produce a three-dimensional model isdescribed in U.S. Pat. Nos. 5,338,198, and 5,452,219 describes a methodfor laser scanning a tooth model and milling a tooth mold. Digitalcomputer manipulation of tooth contours is described in U.S. Pat. Nos.5,607,305 and 5,587,912. Computerized digital imaging of the arch isdescribed in U.S. Pat. Nos. 5,342,202 and 5,340,309.

Other patents of interest include U.S. Pat. Nos. 5,549,476; 5,382,164;5,273,429; 4,936,862; 3,860,803; 3,660,900; 5,645,421; 5,055,039;4,798,534; 4,856,991; 5,035,613; 5,059,118; 5,186,623; and 4,755,139.

Realistic simulations of teeth position are extremely helpful to manyorthodontic treatment processes. Orthodontists may use plaster models ofthe upper and lower arch, to create a set-up that may be manipulated tomodel the starting and finishing positions of teeth. Thus, the teeth maybe modeled to help eliminate guesswork. Brackets may be bonded to eachtooth model to show the orthodontist the geometry of the wire to runthrough the bracket slots to achieve a desired result. The bracketposition may then be transferred to the original malocclusion model. Tomake sure that the brackets will be bonded at exactly this position atthe real subject's teeth, small templates for every tooth can befabricated that fit over the bracket and a relevant part of the toothand allow for reliable placement of the bracket on the subject's teeth.Alternatively, a transfer tray may be fabricated for each arch byplacing each single bracket onto a model of the malocclusion and thenfabricating a single transfer tray per arch that covers all brackets andrelevant portions of every tooth. Thus, a transfer tray may help assurea very quick and yet precise bonding using indirect bonding.

U.S. Pat. No. 5,431,562 to Andreiko et al. describes a computerized,appliance-driven approach to orthodontics in which shape information ofteeth is acquired and a target archform is calculated from the shapeinformation. The shape of customized bracket slots, the bracket base,and the shape of the orthodontic archwire, are calculated in accordancewith a mathematically-derived target archform. However, the orthodontistdoes not substantially interact with the appliance design.

Align Technologies also offers transparent, removable aligning devices.In this system, an orthodontist obtains an impression model of asubject's dentition and ships this model to a remote appliancemanufacturing center, where it is scanned with a CT scanner. A computermodel of the dentition in a final target situation is generated at theappliance manufacturing center and made available for viewing to theorthodontist over the Internet. The orthodontist indicates changes he orshe wishes to make to individual tooth positions. Later, another virtualmodel is provided over the Internet and the orthodontist may review therevised model and indicates any further changes. After several suchiterations, the target situation is agreed upon. A series of removablealigning devices (or shells) are then manufactured and delivered to theorthodontist. The shells, in theory, will move the subject's teeth tothe desired or (final) target position.

The coordination of the different steps of the treatment (the overalltreatment process) typically involves early input from the practitioner(e.g., doctor, dental technician, etc.) in forming the aligner designreferencing only the initial dental alignment of the subject. Mosttreatment processes do dynamically react to the ongoing treatment of thepatent by the dental aligner. Thus, it may be difficult to optimize theinteraction between the practitioner and the ongoing aligners produced.

U.S. Pat. No. 6,699,037 by Align Technology describes improved methodsand systems for repositioning teeth from an initial tooth arrangement toa final tooth arrangement. Repositioning is accomplished with a systemcomprising a series of appliances configured to receive the teeth in acavity and incrementally reposition individual teeth in a series of atleast three successive steps. The individual appliances preferablycomprise a polymeric shell having the teeth-receiving cavity formedtherein, typically by stereo lithographic molding. Each individualappliance is configured so that its tooth-receiving cavity has ageometry corresponding to an intermediate or end tooth arrangementintended for that appliance. That is, when an appliance is first worn bythe subject, certain of the teeth will be misaligned relative to anundeformed geometry of the appliance cavity. The appliance, however, issufficiently resilient to accommodate or conform to the misaligned teethand will apply sufficient resilient force against such misaligned teethin order to reposition the teeth to the intermediate or end arrangementdesired for that treatment step.

U.S. Pat. Nos. 6,471,511 and 6,682,346 describe Align Technology'sstereo lithographic fabrication process. Several drawbacks exist howeverwith the stereo lithography process. The materials used by stereolithography processes may be toxic and harmful to human health. Stereolithography builds the aligner layer by layer, which may create spacessusceptible to the growth of germs and bacteria when it is worn by asubject. Furthermore, Align Technology's stereo lithography process alsorequires a different aligner mold at each stage of the treatment, whichproduces a lot of waste and is environmental unfriendly. Thus, there isa need for practical, effective and efficient methods to produce adental aligner.

Modeling a subject's teeth, such as modeling the upper or lower dentalarches (including the manner in which the teeth interact) may be animportant feature in using and creating an alignment device. A model ofthe subject's teeth can help guide the desired movement of the subject'steeth during an orthodontic treatment. The model can help avoidinterference between a subject's teeth when undergoing dentalre-alignment. A model can also provide input for the design andmanufacturing of dental aligner devices. Thus, there is a need toaccurately and efficiently obtain models of subjects' dental arches,including both virtual and actual models.

Another challenge for orthodontic treatment using aligning devices is toaccurately translate the subject's teeth movement into treatmentmeasures in the iterative treatment progress. The current treatmenttechniques are not able to quantitatively monitor the teeth movement ofthe subject's teeth and precisely adjust the treatment in accordance tothe teeth movement of the subject's teeth.

Another challenge for orthodontic treatment using removable aligningdevices is to accurately and most effectively render teeth movement. Thecurrent treatment techniques are often unable to account for the realand least resistance movement of the subject's teeth, which results inwanted teeth movement and/or unnecessary number of treatment steps.

By tracking the relative positions of the teeth in the upper and lowerarches, dental aligner devices can be designed and fabricated to reflectthe ongoing treatment by an orthodontist or user, as well as the effectof the treatment on the subject. This may ultimately save in cost,treatment time, and may also enhance user comfort.

Finally, the dental treatment processes may be designed to allowmodification of the treatment steps based on the movement of thesubject's teeth. Furthermore, there is a need for more optimal treatmentprocesses, including the manufacturing of the dental aligners. Describedherein are devices, systems, and methods which may address some of theproblems described above.

SUMMARY OF THE INVENTION

The present invention provides methods, systems, and apparatus todesign, manufacture and use dental alignment devices based on asubject's dental arches. Implementations of the methods, devices andsystems described herein may include one or more of the following.

Generally described herein are methods of moving a subject's teeth(e.g., treating a subject) in which one or more aligners is provided toa subject to wear, so that the aligners may exert force to move thesubject's teeth. The aligners may be designed as part of a series ofaligners to be worn. The series may be determined based on the subject'sinitial teeth position, and based on input from a user (e.g., apractitioner such as a doctor, orthodontist, technician, etc.). In somevariations, the treatment series (and therefore the aligners) may bedesigned based on feedback from the subject's teeth position as one ormore of the aligners is worn. In some variations, the user may modifythe series during treatment. In some variations, the series isdetermined based on one or more constrained directions of motion (e.g.,in a translational direction or a rotational direction of an individualtooth). Specific variations and examples of the devices, methods andsystems are provided.

Described herein are methods for producing a dental aligner to move asubject's teeth. In general, these methods may include the steps ofproducing a tooth model simulating the tooth body of one of thesubject's teeth, affixing to the tooth model one or more registrationfeatures simulating the roots of the subject's tooth, producing a dentalbase having one or more receiving features configured to receive thetooth model, and fabricating a dental aligner using the tooth modelattached to the one or more receiving features on the dental base.

The step of fabricating a dental aligner may include producing aplurality of tooth models simulating the tooth bodies of the subject'steeth, assembling the physical tooth models on the dental base to form aphysical arch model, and fabricating the dental aligner using thephysical arch model attached to the dental base. The registrationfeatures on the physical tooth model may comprise pins or protrusions,and the receiving features may comprise sockets, slots or holes. Thereceiving features generally mate with the registration features. Insome variations included herein, the receiving features may comprisepins or protrusions, and the registration features may comprise sockets,slots or holes. Any appropriate registration features and receivingfeatures may be used.

A tooth model may be produced by producing a physical arch model of thesubject's teeth using an impression of the subject's teeth andseparating the physical arch model into one or more tooth models. Adental aligner may be fabricated by vacuum forming the dental alignerusing a sheet of aligner-making material over the tooth model attachedto the dental base, or by CNC manufacture, or by casting.

Also described herein are systems for moving a subject's teeth, whichmay include a plurality of physical teeth models each having one or moreregistration features (wherein the registration features simulate theroots of the subject's teeth and wherein each tooth model comprises atooth body formed from a model of the subject's tooth), a dental basecomprising one or more receiving features (the dental base configured toreceive the plurality of teeth models to form a physical dental archmodel corresponding to a target configuration of the subject's dentalarch), and a dental aligner fabricated using the plurality of physicalteeth models attached to the dental base, so that the dental alignercorresponds to the target configuration of the subject's dental arch.

The dental aligners described herein are generally intended to move asubject's teeth from an initial configuration to a final configuration.Thus, aligners may be used to straighten teeth or correct malocclusion.These dental aligners may move the subject's teeth by rotating and/ortranslating the subject's teeth. For example, the dental aligners mayrotate at least one of the subject's teeth in one or more directionsaround its roots when the aligner is worn by the subject. In particular,a dental aligner may rotate at least one of the subject's teeth aroundits roots in one or more of: the polar direction, the azimuthaldirection, and the self-rotation direction. A dental aligner maytranslate at least one (or more) of the subject's teeth in thex-direction, y-direction, and/or the z-direction.

Another method for treating a subject's teeth includes the steps ofdetermining a target configuration for the subject's teeth, producingreceiving features on a dental base in response to the targetconfiguration (the receiving features being configured to receivephysical tooth models), assembling the physical tooth models on thedental base to form a physical arch model, and producing a dentalaligner using the physical arch model to move the subject's teeth to thetarget configuration. The step of producing receiving features on adental base may include determining the locations of the receivingfeatures on the dental base in response to the target configuration forthe subject's teeth and producing the receiving features at thedetermined locations on the dental base.

As described above, the step of producing receiving features on a dentalbase may involve the steps of producing a subject physical arch model bymolding a malleable casting material using an impression of thesubject's teeth, producing registration features on the subject physicalarch model, and separating the subject physical arch model into aplurality of physical tooth models. Each physical tooth model mayinclude one or more registration features.

Determining a target configuration for the subject's teeth may involvethe steps of determining an initial configuration of the subject'steeth, determining a final configuration of the subject's teeth, anddetermining a target configuration for each of a plurality of treatmentsteps for moving the subject's teeth from the initial configuration tothe final configuration. Receiving and/or registration features on adental base may be fabricated by any appropriate method, including byCNC-based manufacturing, or other computer-controlled methods. In someof the methods, devices, and systems described herein fiduciary marks(e.g., receiving and/or registration features) are fabricated as part ofthe aligner fabrication procedure.

Also described herein are methods for treating a subject's teeth,comprising determining an initial configuration of the subject's teeth,determining a final configuration of the subject's teeth, designing amovement path from the initial configuration to the final configurationfor one or more of the subject's teeth, dividing the movement path intoa plurality of treatment steps (each having a target configuration forthe subject's teeth), producing receiving features on a dental base inresponse to the target configuration for the subject's teeth (thereceiving features being configured to receive physical tooth models),assembling the physical tooth models on the dental base to form aphysical arch model in the target configuration, and producing at leastone dental aligner using the physical arch model configured to move thesubject's teeth to the target configuration.

The step of producing receiving features on a dental base may includedetermining the locations of the receiving features on the dental basein response to the target configuration for the subject's teeth andproducing the receiving features at the determined locations on thedental base. Further, the step of assembling the physical tooth modelson the dental base may include producing physical tooth models from amodel of the subject's teeth, wherein the physical tooth models compriseregistration features configured to be attached to the receivingfeatures on the dental base.

The physical tooth models may be assembled on the dental base byproducing a subject physical arch model by molding a malleable castingmaterial using an impression of the subject's teeth, producingregistration features on the subject physical arch model, and separatingthe subject physical arch model into a plurality of physical toothmodels wherein each physical tooth model includes one or more of theregistration features. The physical tooth models may be fabricated usingCNC based manufacturing, for example, or they may be molded. In general,the dental aligner may be fabricated by vacuum forming the dentalaligner using a sheet of aligner-making material over the physical archmodel, by molding a malleable casting material over physical arch modelin a casting chamber, or by using CNC based manufacturing.

Also described herein are dental treatment systems for moving asubject's teeth. The system may include a storage device configured tostore an initial configuration of the subject's teeth, a finalconfiguration of the subject's teeth, a movement path from the initialconfiguration to the final configuration for one or more of thesubject's teeth, and a target configuration intermediate between theinitial configuration and the final configuration along the movementpath. The system may also include a dental base having receivingfeatures corresponding to the target configuration for the subject'steeth, a physical arch model comprising physical tooth models attachedto the receiving features on the dental base, and a dental alignerproduced using the physical arch model, configured to move the subject'steeth toward the target configuration. The storage device may be acomputer, which may be configured to control the fabrication ofreceiving features on the dental base at locations in response to thetarget configuration for the subject's teeth.

Also described herein are dental treatment systems for moving asubject's teeth that include a computer configured to store a targetconfiguration for the subject's teeth, a dental base having receivingfeatures corresponding to the target configuration stored in thecomputer, one or more physical tooth models configured to attached tothe receiving features on the dental base, and a dental aligner producedusing the one or more physical tooth models attached to the dental base.Because it is produced from the physical tooth models attached to thedental arch, the aligner is configured to move the subject's teethtoward the target configuration. The computer may be configured tocontrol the fabrication of receiving features on the dental base atlocations in response to the target configuration. The computer may alsobe configured to store an initial configuration of the subject's teethand a final configuration of the subject's teeth, and a plurality oftarget configurations corresponding to treatment steps from the initialconfiguration to the final configuration.

Also described herein are dental treatment systems for moving asubject's teeth. These systems may include a physical arch modelcomprising one or more physical tooth models each having one or moreregistration features, a dental base having receiving featuresconfigured to receive the registration features of the physical toothmodels to form the physical arch model, a computer system configured tostore a target configuration for the subject's teeth and to control thefabrication of the receiving features on the dental base, and a dentalaligner produced using the physical arch model, configured to move thesubject's teeth toward the target configuration.

The computer system may be configured to determine the locations of thereceiving features on the dental base in response to the targetconfiguration for the subject's teeth to control the fabrication of thereceiving features at the determined locations on the dental base. Thecomputer may also be configured to store an initial configuration of thesubject's teeth and a final configuration of the subject's teeth, and todetermine target configurations for a plurality of treatment steps fromthe initial configuration to the final configuration.

Also described herein are dental treatment systems for moving asubject's teeth comprising a computer system configured to store atarget configuration for the subject's teeth, one or more physical toothmodels comprising registration features, a dental base having receivingfeatures to receive the registration features, a device configured tofabricate the receiving features on the dental base in response to thetarget configuration under the control of the computer system, and adental aligner formed over the physical tooth models attached to thedental base, wherein the dental aligner is configured to move thesubject's teeth toward the target configuration.

Also described herein are dental treatment methods for moving asubject's teeth having feedback. This method of dental treatment mayinclude the steps of producing a first dental aligner for moving thesubject's teeth toward a first target configuration, analyzing thepositions of the subject's teeth after the subject has worn the firstdental aligner, determining a second target configuration in response tothe position of the subject's teeth after the subject has worn the firstdental aligner, and producing a second dental aligner for moving thesubject's teeth toward the second target configuration. The step ofproducing a second dental aligner for moving the subject's teeth towardsa second target configuration may involve producing a dental base havingreceiving features (wherein the receiving features correspond to thesecond target configuration for the subject's teeth, the receivingfeatures configured to receive physical tooth models), assembling thephysical tooth models on the dental base to form a physical arch model,and forming a second dental aligner using the physical arch model.

The method may also include the step of creating physical tooth modelsfrom the subject's dental arch by producing a template physical archmodel using an impression of the subject's teeth, incorporatingregistration features in the template physical arch model, andseparating the template physical arch model into a plurality of physicaltooth models wherein each of the physical tooth models includes at leastone registration feature. The method may further comprise determining afinal target configuration of the subject's teeth, wherein the firstdental aligner and the second dental aligners move the subject's teethtowards the final target configuration. Analyzing the position of thesubject's teeth after the subject has worn the first dental aligner mayinvolve producing an impression of the subject's teeth after the subjecthas worn the first dental aligner and measuring the positions of thesubject's teeth using the impression of the subject's teeth.

Also described herein are dental treatment systems for moving asubject's teeth, comprising a first dental aligner configured to movethe subject's teeth toward a first target configuration, a measurementdevice configured to determine the positions of the subject's teethafter the subject has worn the first dental aligner, a dental basehaving receiving features for receiving physical tooth models, and ananalysis device configured to assist a technician in determining asecond target configuration based on the positions of the subject'steeth after the subject has worn the first dental aligner (wherein theanalysis device is further configured to form the receiving features ofthe dental base so that they correspond to the second targetconfiguration). The measurement device may be a mechanical locationdevice or an optical scanner. The analysis device may include a computerconfigured to manipulate a digital model of the subject's teeth, whereinthe analysis device comprises constraint logic indicating constraints onmovement to of the teeth, as described further herein.

Also described herein are methods of fabricating a dental aligner for asubject, comprising determining an initial configuration of thesubject's teeth, determining a target configuration of the subject'steeth from the initial configuration (wherein the teeth in the targetconfiguration are moved from the initial configuration under theconstraint of no movement in at least one degree of freedom), andproducing a physical model of the dental arch having physical toothmodels arranged in the target configuration. The initial configurationmay reflect the current configuration of the teeth in the subject'sdental arch. The step of determining a target configuration may involvemanually determining a target configuration and may be aided by using ananalysis device comprising constraint logic that indicates constraintson the movement of the teeth. The degree of freedom is typicallyselected from the group of the x-direction, the y-direction, thez-direction, the polar direction, the azimuthal direction, and theself-rotation direction. The constraint of no movement may mean notranslational movement of the teeth in the x-direction, the y-direction,or the z-direction, or no rotations of the teeth around the roots of thetooth in the polar direction, the azimuthal direction, or theself-rotation direction.

Also described herein are dental treatment system for fabricating adental aligner with movement constraints. This system may include ananalysis device configured to allow manipulation of a model of thesubject's dental arch from an initial configuration to a targetconfiguration, wherein the analysis device comprises constraint logicindicating constraints on movement of the subject's teeth in thedirection of one or more degrees of freedom. The system may also includea plurality of physical tooth models configured to form a subject'sdental arch (the physical tooth models having registration featurescorresponding to the roots of the subject's teeth), and a dental basehaving receiving features configured to receive the physical toothmodels so that the physical tooth models are arranged in the targetconfiguration.

This analysis device may include a computer device configured todecouple the movements of the subject's tooth to rotations around theroots of the subject's tooth and translations of the subject's tooth. Asdescribed above, the degree of freedom may be selected from the group ofthe x-direction, the y-direction, the z-direction, the polar direction,the azimuthal direction, and the self-rotation direction.

The disclosed devices, methods and systems may provide dental alignerdevices. The dental aligner devices so obtained are effective atre-aligning the teeth and may have enhanced comfort when worn. Thedisclosed devices, systems and methods may significantly reduce thetreatment time and cost compared to the prior art systems. Physicaltooth models and the dental base can be shared between treatment steps.Physical arch models can be configured and re-configured for differenttreatment steps. The physical tooth models can be used to form differentarch models in different treatment steps, which may significantly reducetreatment costs and cycle time required for each treatment step. Adental base can include a plurality of target configurations each fordifferent treatment steps. The costs of the dental base can be sharedbetween treatment steps. Dental aligners can be conveniently andinexpensively fabricated using the physical arch model.

The details of one or more embodiments are set forth in the accompanyingdrawing and in the description below. Other features, objects, andadvantages of the invention will become apparent from the descriptionand drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention:

FIG. 1A is a flow chart for providing accurate orthodontic treatment fora subject in accordance with the present invention.

FIG. 1B is a flow chart showing another variation of the dentaltreatment method having feedback as described herein.

FIG. 2 illustrates an exemplified mechanical location device foracquiring the surface locations of dental impression and subject's teethpositions.

FIG. 3A illustrates a subject's tooth and decoupling of movements.

FIG. 3B illustrates a tooth model that can simulate the movements of thesubject's tooth in FIG. 3A.

FIG. 3C illustrates a tooth model having registration features.

FIG. 4 illustrates a system for producing receiving features on a dentalbase for receiving physical tooth models.

FIG. 5 is a top view of a dental base comprising a plurality of socketsfor receiving pins affixed on the physical tooth models.

FIG. 6 illustrates a physical tooth model comprising two pins that allowthe physical tooth model to be plugged into two corresponding sockets ina dental base.

FIG. 7 illustrates an arrangement of fabricating a dental aligner usinga dental arch model.

FIG. 8 shows a flow chart describing one variation of a treatment methodfor treating misaligned teeth as described herein.

DESCRIPTION OF INVENTION

The following detailed description should be read with reference to thedrawings. The drawings, which are not necessarily to scale, depictselective embodiments and are not intended to limit the scope of theinvention. The detailed description illustrates by way of example, notby way of limitation, the principles of the invention. This descriptionwill clearly enable one skilled in the art to make and use theinvention, and describes several embodiments, adaptations, variations,alternatives and uses, including what is presently believed to be thebest mode of carrying out the invention.

It is to be understood that unless otherwise indicated, the methods,systems and devices described herein need not be limited to applicationsin orthodontic treatments. As one of ordinary skill in the art havingthe benefit of this disclosure would appreciate, variations may beutilized in various other dental applications, such as fabrication ofand/or treatment planning for dental crowns, dental bridges, andaligners. The dental models may also be modified to support researchand/or teaching applications. Moreover, it should be understood thatvariations of the methods, devices and systems described herein may beapplied in combination with various dental diagnostic and treatmentdevices to improve the condition of a subject's teeth.

It must also be noted that, as used in this specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, the term “a tooth” is intended to mean a single tooth or acombination of teeth, “an arch” is intended to mean one or more arches(e.g. both upper and lower dental arches). Furthermore, as used herein,“calculating,” and “formulating” may include the process of utilizingmanual and/or computer calculations, such as those used to create anumeric representation of an object (e.g., a digital model) or tomeasure differences in tooth position. For example, a digitalrepresentation may comprise a file saved on a computer, wherein the fileincludes numbers that represent a three-dimensional projection of atooth arch. In another variation, a digital representation comprises adata set including parameters that can be utilized by a computer programto recreate a digital model of the desired object.

Described herein are treatment methods for treating a subject'smisaligned teeth. FIG. 8 illustrates a schematic overview of thetreatment method. This method generally includes steps of analyzing thesubject's dental arches 801, formulating a treatment plan 803, beginningthe treatment plan 805, monitoring the treatment plan 807, revising thetreatment plan if necessary 809, and continuing the treatment plan untila desired endpoint is achieved 811.

The treatment plan may include any appropriate treatment plan, buttypically includes designing and providing a dental appliance (alsoreferred to as a dental aligner) to alter the subject's dental arch. Thetreatment plan may include steps for analyzing the subject's dentalarch, modeling the dental arch, and designing a dental arch to be wornby the subject to alter the dental arch in a desirable manner. Thetreatment plan may also include steps for preparing the subject's dentalarch (e.g., by extracting, shaping, trimming, or otherwise altering oneor more of the subject's teeth). Finally, the treatment plan may includesteps for designing one or a series of dental aligners, and forfabricating one or a series of dental aligners.

Provided below are examples of treatment methods, including specificsteps which may be included as part of a treatment method, or featuresof the treatment method. In particular, dental aligners that are used aspart of a treatment method are described.

Treatment Method

The treatment methods described herein include steps for fabricating ofone or more dental aligners. Dental aligners (aligners) may be formed asa series of polymeric dental aligners molded over tooth models. Thisstep typically includes forming sheets of standard, dental grade polymer(e.g., dental grade polymer available from RainTree Essix) over modelsof the subject's dental arch fabricated from an epoxy cast of thesubject's actual teeth, then hand trimming and polishing them to conformto the subject's gingiva.

Separate computerized processes may facilitate the process. For example,a software program may facilitate on-line communication with a dentalpractitioner, (e.g., orthodontist, doctor, etc.). The subject's dentalarch (e.g., dental models) may be scanned to record the tooth positionsto help the technician or practitioner manipulate a 3D model of theteeth to graphically depict tooth movement. The recorded tooth positionson the manipulated 3D model may then direct a CNC (Computer NumericalControlled) machine to drill holes in a base plate into which theindividual, epoxy cast teeth are placed for forming. Thesecomputer-aided processes expedite the process of mass aligner productionthe core action of fabricating aligners. A practitioner mayprogressively adjust the epoxy tooth arrangements to create a new modelon which to heat-form aligners. Further description of thecomputer-assisted steps and method of forming a dental aligner may befound in co-pending PCT application titled “COMPUTER AIDED ORTHODONTICTREATMENT PLANNING”, by Huafeng WEN, Muhammad Ziaullah Khan CHISHTI,Frank Zhenhuan LIU, Kashif MOHAMMED, Syed Wasi Mohsin Raza RIZVI, andYasser BASHIR, herein incorporated by reference in its entirety.

The practitioner may communicate his or her instructions and adjustmentsover the course of the treatment process, so that the manufacture ofsequential aligners for an individual subject may be modified during thetreatment process. Furthermore, individual subject information (e.g.,response to treatment) may be incorporated into the design of the dentalaligner, and into the overall treatment method. For example, writteninstructions and the manipulation of 3D graphics (e.g., digital dentalmodels) may be used to modify the design of dental aligners. Thiscommunication may allow a technician to precisely follow instructions orcomments from the dental care practitioner (or subject) during each stepin aligner fabrication. In contrast, other aligner fabricatorstechniques do not afford the practitioner the opportunity to adjustaligners (and therefore treatment) on a continuing basis; instead, acomputer algorithm determines the tooth movement and the practitioner orsubject receives several years worth of dental aligners for treatment ata single time.

The treatment methods described herein provide the practitioner theopportunity to review the treatment (e.g., the current tooth positionduring treatment) and to modify the treatment by modifying the alignershape, and effect on the dental arch at appropriate times (e.g., beforethe next aligner is fabricated).

An exemplary treatment method begins with an analysis of a subject'sdental arch. For example, a practitioner (e.g., a doctor, such as adentist or orthodontist, technician, or the like) may make an impressionof the subject's teeth and gingiva. Impressions are typically taken ofboth the upper and lower jaw. The impressions may be prepared usingstandard techniques, such as a dental tray filled with polyvinysiloxane(PVS). In addition to trays with the impressions, a Panorex, biteregistration, intra-oral photographs, extra-oral photographs, and awritten prescription describing the professional's desired repositioningof the subject's teeth may be used to manufacture a model (or models) ofthe subject's dental arch, and to help design the subject's treatmentplan. As mentioned, a practitioner may submit instructions orobservations (e.g., a prescription) describing a desired dentalarrangement, or manner of achieving a desired dental arrangement. Thisprescription may be based upon the professional's observations of thelocations of the subject's teeth and possible improvements thereof. Thisprescription may be transmitted in any appropriate form, including beingwritten on a form that has blanks for identifying which teeth are to betreated, what treatment is desired. The prescription may be freeform ormay include a menu of choices. In some variations, the prescription mayinclude specific points such as the inter-proximal reduction (IPR)desired and may include observations such as which teeth are faciallyrestored (and therefore should not receive anchoring buttons), mayinclude existing occlusion information, may indicate where extractionsare to be performed, and/or may indicate other specifics of thetreatment to be applied. This information from the practitioner may alsobe entered into a computerized form by the practitioner in his or heroffice and made available on-line via for review by other practitionersor by the aligner manufactures.

This dental impression, images, and any other data collected from thesubject's dental arch may be analyzed in order to model the subject'sdental arch. For example, a device called a MicroScribe may be used toidentify the location and orientation of each tooth within both theupper and lower impression. Such positional information may then used(e.g., by a CNC machine) to create a “base plate” for modeling thedental arch. The process of modeling the dental arch is described inmore detail below, as well as in the references previously incorporated.One variation of this process is summarized here to illustrate atreatment method. A base plate may be used to form a physical model ofthe dental arch that may also be used to form a dental aligner. Forexample, the base plate may have holes drilled in locations andorientations corresponding to the positions of the teeth roots. Pins maybe placed into these holes, and may act as fiduciary markers, as well ashelping to model the movement and position of the teeth. In onevariation, pins are approximately 1.6 mm diameter and extend outwardlyfrom the base plate approximately 5 mm.

The subject's dental arch impression (e.g., PVS impression) may then beplaced into a casting container along with the above-mentioned baseplate with the pins inserted. The impression may then be cast (e.g.,using a hard epoxy-type material) to form a precision duplicate of asubject's teeth with metal pins embedded inside each tooth. After theepoxy hardens, the castings can be removed from the impressions, formingpositive models of the subject's teeth in their initial untreatedpositions (as well as the subject's gingiva).

In some variations, two model arches, one for the upper arch and one forthe lower arch, are made, and put together with the PVS Bite provided.Known points on the 2 arches may be measured to determine the biterelationship between the two arches.

The base plate can then be removed from the positive model. The positivemodels are cut apart so that each section of the model comprises oneindividual model tooth and the adjacent gingiva. Typically, each modeltooth with its gingiva has two pins protruding from it. As mentioned,these pins may act as both fiduciary markers showing the relativeorientation of the teeth with respect to each other and may alsorepresent “roots” of the teeth.

Each model tooth can then be individually scanned with a Laser scannerto generate a three-dimensional computer model of the tooth, whichincludes the exposed surfaces of the model tooth, and the positions andorientations of the two pins that extend from the tooth. A computermodel of the arch may be re-constructed based on the scan data. Thestored pin positions and the stored virtual model teeth are combinedwith a random positional generator to create a digital model of thedental arch. For convenience, this digital dental arch is referred toherein as the “working arch.”

The positions of the subject's teeth in the virtual (e.g., working)arch(es) may be manipulated into a desired position based upon the inputfrom the practitioner (e.g., the written input provided). A technicianmay use the digital model to create a target arrangement (typically anintermediate target arrangement) of the dental arch from the workingarch. In some variations, the physical march is manipulated to form thetarget dental arch. The dental arch may be manipulated into a targetdental arch by the technician or practitioner. The technician may applyhis or her own experience in forming the target arrangement of thedental arch, as well on guidelines set by the practitioner. In somevariations, the technician forms the target dental arch based onmovement constraints implicit in the movement of the subject's teeth, asdescribed further below. A digital model formed by the targetarrangement may also be referred to as a “prescription view” (or“RxView”) of the virtual tooth positions, in the virtual arch(es).

The target arrangement of the dental arch may be the final targetarrangement, in which the teeth are arranged in a desired finalposition, or it may be an intermediate target arrangement, in which theteeth are being moved toward the final target arrangement. Each targetarrangement (both intermediate and final) may be associated with one ormore dental aligners.

Thus, a RxView is typically a visual representation of the technician'sinterpretation of the prescription from the doctor. Typically, thisRxView (digital dental arch model) is not used to fabricate an aligner.For example, this digital dental arch model may have teeth that havesmall gaps which may not reflect a good treatment, and the teeth mayeven overlap with each other. The RxView is typically a visual guidethat does not direct the physical placement of the epoxy teeth modelsused, as described below, to generate the aligner.

RxView data may be disseminated to the practitioner. For example, viasoftware running on a web-based account. The practitioner can theneither modify the digital dental arch model (RxView) using software orcan send comments suggesting further modification of the target dentalarch model. A technician may incorporate these comments.

For example, a technician may manipulate the positions of the subject'steeth in the digital model (either the initial model or the RxViewmodel) using a computer program. The teeth of the dental arch may bemanipulated into a position so that an aligner formed to correspond tothis position (the “next appliance position”) will move the teeth towardthe desired alignment. Thus, in the first pass, the dental arch modelwill be in a “current position” (reflecting the current position of theteeth) and can be moved into the “next appliance” position which isfirst appliance position. In one variation of this process, the RxViewmay be used by the technician as a visual reference, but it is typicallynot a source of digital information used in the manipulations performedby the technician. Rather, the technician's manipulations of the currenttooth positions are based upon the technician's visual judgment of howthose current positions relate to the desired positions as visuallyrepresented in the RxView and based upon the judgment in thetechnician's mind of the best approach to moving the teeth from theircurrent positions toward those desired positions.

During this step, the software may impose anatomically-derivedlimitations (constraints) on the extent of movement and/or force appliedto each tooth, e.g., limiting movement to 0.3 mm or less. When toothmovements are completed, the technician typically stores the new virtualarches (having teeth positions corresponding to the positions of theteeth to be achieved by the next appliance). These “next appliance”digital models may include simulated gingiva and roots that may beappended to the exposed surfaces of the teeth that are included in thevirtual model teeth.

Prior to manufacture of an aligner using the device, a practitioner maybe notified that the “next appliance” model is ready and can bereviewed. The practitioner may view the virtual arch(es) of the virtualmodel teeth in their current untreated positions, the virtual arch(es)of the virtual model teeth in the RxView, and the virtual arch(es) ofthe virtual “next appliance” model teeth as they will be positioned bythe forthcoming aligner. The practitioner can modify both the RxViewtooth positions, and the positions for the next appliance, usingcontrols by which a tooth may be selected and moved, as described inmore detail in some of the patent applications previously incorporatedby reference. Typically, the practitioner eventually approves (e.g., viacomputer access), the (potentially modified) RxView and the (potentiallymodified) virtual arch tooth positions for the next appliance. The “nextappliance” will then be the manufactured. In some variations, multiple(e.g., two) appliances are manufactured at a time. Thus, both animmediately “next appliance” and the appliance following the “nextappliance” may be modeled (digitally) and then fabricated as describedabove.

As described in more detail below, the aligner manufacturing process isused to produce one or more dental aligners using the digital model byforming a physical (non-digital model). Once the RxView is finallyapproved by the practitioner, the locations of the pins in the virtualmodel teeth for the first appliance may be used to program a CNCmachine, to drill holes (e.g., receiving features) in a staging plate orplates (also referred to as a base plate) that correspond to thepositions of the pins of the model teeth for the forthcoming appliance.Model teeth with pins are manually inserted into the holes in thestaging plate(s) drilled by the CNC machine, creating a physicalarrangement of the teeth in the positions for the appliance to beformed.

An aligner may then be fabricated over the model teeth that arepositioned in the staging plate(s), using a “drape and form” processwith a dental pressure forming machine, and the aligner can then betrimmed. Aligners may also be fabricated with special features requestedby the practitioner, such as buttons and windows to assist certain teethmovement. For example, buttons and windows may be used to help securethe aligner to the dental arch and may be used to direct force to movethe teeth of the dental arch. For example, if such features arerequested, small buttons can be installed on the model teeth in themanufacturing process. A template plastics tray will be made to assistthe doctors to place the buttons in a subject's teeth. Aligners can thenbe fabricated with windows (e.g., small cut-outs) at the location ofeach prescribed button.

After manufacture, the aligners can be marked for case number andsubject's name (or otherwise labeled), cleaned, sterilized, and packagedfor shipment. In some variations, a box is shipped to the practitionerthat includes two plastic bags containing two sets of appliances formedin the preceding steps, plus the templates for buttons, if any. Thepractitioner examines the appliance (the “next aligner”) on the subjectto test the fit. During the first visit to the practitioner afterimpressions have been made, the “next appliance” will be the firstappliance. If the practitioner deems the aligner fit to be correct, thesubject can leave with the current appliance, and the next appliance,and wears each for three weeks in succession.

During the 6-week period of use of the appliances most recentlydelivered to the subject, a technician may manipulate the “current”positions of the subject's teeth (which are the positions used to createthe appliance(s) most recently delivered to the subject), to move theteeth in the manner the technician believes should be done by the nextappliance. This proposed new position may be made available to thepractitioner for approval or modification, as described above, and maythen be used to form the next appliance, in the manner described above.

The subject typically returns to the practitioner after having worn foreach of the two aligners received for the appropriate time (e.g., threeweeks). The practitioner may then monitor the effect of the aligner useto determine if the subject is progressing as expected, or if thetreatment plan needs to be modified. For example, the practitioner maytake additional images of the subject, or may take additional casts ofthe subject's teeth. The monitoring and analysis of the subject'streatment maybe sent to the manufacturer (e.g., for use by thetechnician manufacturing the aligners). If no modification is necessary,or after modification, the steps of approval, further modification ofthe digital model and manufacture of the new aligners is repeatedsubstantially as described above.

These steps may be repeated until the practitioner and/or subjectdiscontinue the treatments. Discontinuing the treatment typically meansthat the treatment goal has been reached, treatment is terminated, orthe practitioner or subject aborts the treatment.

The steps of the treatment methods described herein may includeadditional step, or may omit steps. Furthermore, any appropriate methodmay be used to perform the different steps included. For example, anyappropriate method or device may be used for designing and forming adental aligner

by modeling the dental arch. In some variations, an aligner is formed byfirst modeling the dental arch.

Dental Model

A dental model may be created from an actual image, imprint orreproduction of a subject's tooth or teeth, or a model may be producedfrom measurements or other information derived from a subject orrepresentation of a subject. As used herein, unless the context makesclear otherwise, the terms “model,” “dental model,” “tooth model,” and“arch model” may refer to actual (e.g., physical) or virtual (e.g.,digital) models. Further, the models described herein may include all orportions of a single tooth, all or portions of multiple teeth, and allor portions of the dental arches (including the gingival, tooth, root,jaw, etc.). Thus, the models described herein may include informationabout or representation of any of the features of the dental arches,particularly those features that are relevant to the function andappearance of teeth. For example, the model may represent toothappearance (e.g., location, size, position, color, shape, orientation,texture, etc.), interaction (e.g., proximity to other dental andmandibular features, kinetics, etc.) and the like.

As used herein, a “subject” may include any subject (human or animal)whose dental structure (e.g., teeth, gingival, etc.) may be modeled bythe devices, methods, and systems described herein, includingorthodontic patients.

There are many uses for models of a subject's teeth. In particular, themodels may be used to understand and to treat a subject's dentalalignment. The models may be manipulatable so that different alignmentsof the subject's teeth may be modeled. In some variations, the modelsmay comprise limitations on the movement or arrangement of teeth(constraints). These constraints may be based on physiologicalconstraints, including the orientation of other teeth, the bitealignment, and the ease or difficulty of moving actual teeth in one ormore directions. The manipulatable models may be digital(computer-manipulatable) or physical models.

1. Creation of a Dental Model

A dental model may be created using any appropriate method. Furthermore,the model may be a physical model or a virtual model. For example,models may be constructed from imprints, molds, measurements, images, ormeasurements of a subject's dental features. One model may be made (orderived) from another model. Thus, a physical model may be made from avirtual model, and a virtual model may be made from a physical model. Inparticular, a model may be altered and then one or more derived modelsmay be generated from the original model. For example, components of amodel (e.g., individual teeth) may be moved slightly to form a secondmodel. Thus, the model may represent the actual arrangement of asubject's teeth, or a derived arrangement. Features not present on asubject's teeth (e.g., crowns, dentures, etc.) may be included as partof the dental model.

In one variation, a model may be generated using a mold (e.g., apositive or negative model) of a subject's upper dental arch and a moldof a subject's lower dental arch. In addition, a registration device(e.g., a bite-down registration device) may also be used to model thesubject's bite registration. Fiduciary references may be used to alignany of the components of the model.

For example, at the start of the modeling procedure, a physical model(e.g., mold or cast) may be made of a subject's upper and lower dentalarches. Any appropriate method of making a cast or model of a subject'sdental arches may be used. In one variation, a negative mold is madefrom all (or a portion) of a subject's upper and lower arches. Forexample, a dental cast made be made showing the arrangement of thesubjects upper and lower teeth with respect to each other. A positivereplica may then be formed using this negative mold. The positive andnegative mold may also be used to accurately model the relationship ofthe individual teeth with respect to each other, as described in many ofthe patent applications mentioned above. Other examples of moldingdental arch models are disclosed in the above referenced U.S. patentapplication Ser. No. 11/013,160 (“System and methods for castingphysical tooth model”), and U.S. patent application Ser. No. 10/979,823(“Method and apparatus for manufacturing and constructing a physicaldental arch model”).

Thus, a dental model may be made for the subject's current arrangementof teeth (or “initial” arrangement). The dental models may include anyfeature of the actual dental arches, or a subset of these features. Forexample, the dental model may include the crown regions of the teeth,the gums (gingival), the roots, etc. Some of these features may beactually measured or derived. For example, the structure and locationsof the roots of the teeth may be calculated (or computer-generated) frommeasurements taken from the crown region or other portions of asubject's teeth or mouth, as described in U.S. Provisional patentapplication titled “COMPUTER AIDED ORTHODONTIC TREATMENT PLANNING” byHuafeng Wen, et al, filed Apr. 19, 2005.

In some variations, the dental model may be made by directly scanning asubject's teeth. For example, an intraoral 3-D imaging device, such asOraScanner® manufactured by OraMetrix®, can be utilized to digitize thesubject's tooth arch. The digital dental arch model is subsequentlysegmented into individual teeth, which comprises digital representationsof the crown portion of the individual teeth. In one application, thescanning of the subject's teeth is conducted at the dentist's office.The data generated from scanning, i.e., the digital representation ofthe subject's arch, is then transmitted over a computer network to areceiving computer for further processing.

A physical dental model may also be used to construct a digital dentalmodel. For example, a positive model of the subject's tooth arch may becreated from a negative impression of the subject's teeth. The teeth ofthe positive mold may then be segmented into individual units (e.g.,teeth) and digitized or scanned by various 3D scanning techniques andreconstructed to digitally represent the subject's upper or lower arch.Examples of appropriate scanning techniques that may be used to create adigital model are described further below. A physical model of thedental arches may also be made from a digital model. For example,physical models of the upper and/or lower arches may be fabricated usingComputer Numerical Control (CNC) manufacturing (such as milling, stereolithography, and laser machining).

It may also be beneficial to include markings such as fiduciaryreferences on the upper and lower arch models.

2. Fiduciary References

Fiduciary references may be used to aligning the teeth to form thedental model. Virtually any mark, object or region of an object may beidentified as a fiduciary reference for purposes of aligning the archmodels. A fiduciary reference may be a stereotyped reference mark bywhich the orientation and/or location of an arch model or components ofan arch model (e.g., individual teeth) may be identified. A fiduciaryreference may include multiple marks, or an asymmetric mark. Foreexample, a fiduciary reference may be a point or set of points scribedonto the arch model or onto an object to which the arch model isattached.

In some variations, a model includes a fixture that may be a plate(e.g., a base plate or dental plate) that is not part of the subject'sactual dental arch, but to which the dental arch model is attached. Thefixture may comprise a fiduciary reference. Components of the dentalarch (e.g., individual teeth models) may be secured to the fixture sothat the dental arch does not change position relative to the fixture.Thus, the fiduciary reference(s) may be marked on the dental arch itselfor it may be marked on the fixture, or both. In one variation, thefixture comprises attachment or receiving sites that mate with fiduciarycomponents on the teeth models to provide fiduciary reference. Thus, thefixture may include engagement surfaces to align (and/or secure) othercomponents of the dental model.

For example, the tooth models may comprise registration featurescompatible with the receiving features on the dental plate. Examples ofregistration features that may be used include, but are not limited topins, protrusions, posts, snaps, and the like. In some variations, theregistration features may model the orientation of the roots of theteeth. In registration systems as described above, the individual toothmodels may be used with different dental plates in order to showdifferent arrangements of the teeth. For example, if a tooth is to bemoved to create a modified dental model, the model may be readilyconstructed by moving the receiving feature on the dental plate andusing the same tooth model. Additional examples of registration featuresare described in the Examples given below.

The location and orientation of the fiduciary marker may be selected bythe user (“user” may refer to the technician, manufacturer or in somecases, practitioner), or may be automatically selected (e.g., as by acomputer). For example, the user may indicate on a scan of the dentalarch where to place registration features (e.g., pins) on each tooth.

Fiduciary references may include any number of markers. For example, asingle fiduciary mark may be used to indicate location and orientationof dental arch components. A fiduciary reference may comprise two,three, or more individual marks. In some variations, the fiduciaryreference is a three-dimensional structure (e.g., a cut, a pit, etc.).In some variations, the fiduciary reference is a two-dimensionalstructure (e.g., a mark). In some variations, the fiduciary referencemay comprise a color or texture that is distinguishable from the rest ofthe dental arch model.

As described, a registration device may be used to more accurately modela subject's dental arches. For example, a bite-down registration devicemay be used, and may comprise a material that conforms to the spacesbetween the upper and lower arches when the subject bites down (e.g., awax bite). Additional materials may be used to form the dental models,including images (scans, X-rays, etc.) and the like.

Scanning

The teeth (e.g., a model of the teeth) may be scanned or measured todetermine the position of the teeth. Any appropriate technique may beused to measure the positions of the teeth, including manualmeasurement, contact scanning and non-contact types of scanning. Contactscanning includes scanning by actual (or computer assisted) measurement,including mechanical location devices such as a Microscribe. The scannermay be used to acquiring coordinates (e.g., 3D coordinates) from thedental arches including the fiduciary references.

For example, a Microscibe is a 3D digitizer that can develop a digitalcomputer model from an existing 3D object. Exemplary Microscribes areavailable from Immersion and Phantom. A contact Microscibe scanner maycomprise one or more mechanical arms that have mechanical joints withprecision bearings including sensors. For example, the Microscibe maymove a stylus over the dental model and record accurate 3D positionaland angular information of the points that the stylus touches. Thus, thestylus may touch (or be directed to touch) the teeth, base plate, andany fiduciary references. The mechanical location device may alsocomprise additional sensors (e.g., a sensor located on the tip of thestylus of a Microscribe) for specifically or automatically detecting thefiduciary reference. Examples of additional sensors include opticalsensors, RF sensors, and the like.

When scanning a physical dental model, the model may be broken intopieces (e.g., by tooth) for scanning of the individual pieces. Theindividual scans may then be re-assembled later (using the fiduciarymarks, for example). Furthermore, it may be advantageous to set or affixthe model (or model pieces) to a scan plate (e.g., a surface from whichthe scanning may take place). For example, the model may be attached toa scan plate that rotates or otherwise moves to position the assembly sothat it might be accurately scanned. In some variations, the assembly issecured to a scan plate.

The dental model (or teeth) may also be scanned by non-contact methods.Examples of 3D non-contact scanners and scanning techniques include, butare not limited to, laser scanning, optical scanning, destructivescanning, CT scanning, and sound wave scanning. In some variations,images (e.g., X-rays, etc.) may be analyzed to determine the position ofdental components. This analysis may include image analysis techniques,such as tomography.

The scanner may communicate with a computer that may be used to controlthe scanning, and/or to store information from the scan. Position andorientation information can be obtained, stored and analyzed. Thecomputer may also act as a controller, and may control other portions ofthe scanning process, including the scan plate. For example, thecomputer may allow user input, and may also provide output.

For each portion of the dental model, a fiduciary reference may also bescanned as part of the individual scans, and digital models of the teeth(dental arches) are made from these scans. Each digital model may haveits own coordinate system. In some variations, an individual arch may bescanned in pieces or sections, and later reconstructed to form a modelof a single dental arch, having a single coordinate system.

Based on the positional information identified from the scanning, therelative positions of the teeth may be calculated, and movement of theteeth after or between treatment steps may be measured.

Aligners

The term “dental aligner” may refer to a dental device for renderingcorrective teeth movement or for correcting misaligned teeth. One ormore dental aligners can be worn on the subject's teeth so that asubject wearing the dental aligners will gradually have his or her teethrepositioned by the dental aligner “pushing” (or pulling) against theteeth, or gums (gingiva).

Aligners may be fabricated from the dental models described herein.Details of fabricating dental aligners are disclosed in the abovereferenced U.S. patent application Ser. No. 10/979,497, titled “Methodand apparatus for manufacturing and constructing a dental aligner” byHuafeng Wen, filed Nov. 2, 2004, U.S. patent application Ser. No.11/074,301, titled “Dental aligner for providing accurate dentaltreatment” by Liu et al, filed Mar. 7, 2005, U.S. patent applicationSer. No. 11/074,297, titled “Producing wrinkled dental aligner fordental treatment” by Liu et al, filed Mar. 7, 2005, U.S. patentapplication Ser. No. 11/074,300, titled “Fluid permeable dental aligner”by Huafeng Wen, filed Mar. 7, 2005, and U.S. patent application Ser. No.11/074,298, titled “Disposable dental aligner by Huafeng Wen, filed Mar.7, 2005.

Any appropriate fabrication method may be used to form a dental alignerfrom the dental model. For example, a dental aligner can be made bymolding a malleable casting material in a casting chamber. The mold caninclude at least a portion of a dental arch model. The dental arch modelcan include a plurality of the subject's physical tooth models that arepositioned in the target configuration specified for the specifictreatment step.

The dental aligners can also be fabricated by a Computer Numeric Control(CNC) based manufacturing. A CNC based drilling or milling machine canreceive a digital aligner model as input and produce a dental alignercompatible with the target configuration at the specific treatment step.Details of producing physical dental arch model and associated base aredisclosed in the above referenced and commonly assigned U.S. patentapplication Ser. No. 10/979,823, titled “Method and apparatus formanufacturing and constructing a physical dental arch model” by HuafengWen, filed Nov. 2, 2004, U.S. patent application Ser. No. 10/979,497,titled “Method and apparatus for manufacturing and constructing a dentalaligner” by Huafeng Wen, filed Nov. 2, 2004, U.S. patent applicationSer. No. 10/979,504, titled “Producing an adjustable physical dentalarch model” by Huafeng Wen, filed Nov. 2, 2004, and U.S. patentapplication Ser. No. 10/979,824, titled “Producing a base for physicaldental arch model” by Huafeng Wen, filed Nov. 2, 2004. The disclosure ofthese related applications are incorporated herein by reference.

In one variation, the dental aligner is formed from a dental model byvacuum forming. For example, a sheet of aligner-making material isattached to a sheet holder and then lifted up near a heating element.The sheet can be made of uniform distribution of a single material orcomprise multiple layers of different materials. After thealigner-making material is heated by a specified time, the sheet holderis pressed on the subject's dental arch model on the base plate. Avacuum pump removes air at the bottom of the base plate to cause thesoftened aligner making material to relax and fittingly form around thesurface the subject's dental arch model. This process of aligner makingis referred to as the vacuum forming.

In one embodiment, the subject's dental arch model includes throughholes which may mate with connectors attached to the subject's teeth.Examples of such snap-on aligner are described in U.S. ProvisionalApplication, titled, “DENTAL ALIGNER DEVICES HAVING SNAP-ON CONNECTORS,”by Huafeng Wen, et al. filed Apr. 15, 2005, herein incorporated byreference in its entirety.

One or a plurality of dental aligner can be provided to the subject ateach step of the dental treatment. Each of the aligners can be worn fora period of time from a few hours to a few weeks. The teeth movementcaused by the dental aligner is normally not exactly the same asdesigned by the treatment plan.

In general, aligners are fabricated so that they apply force to move theteeth, resulting in the re-alignment of the teeth. Thus, aligners aretypically fabricated using models that represent the teeth in positionswhich have been shifted slightly in a direction leading to a desiredalignment position, so that the teeth will tend to move towards thedesired position. The selection of the ultimate (e.g., desired) positionof the teeth, as well as the movement path to move the teeth into thedesired position may be chosen by an orthodontist.

Selecting the Movement Path

A dental model may be used to determine a final position for aligningteeth. For example, an orthodontist may manipulate a dental model todetermine the final alignment position of the teeth. In some variations,the orthodontist may use computer software to determine the finalposition of the teeth. The final position of the teeth may be used todetermine a movement path in order to move a subject's teeth from afirst position (e.g., the initial position or a subsequent positionafter staring the alignment process) to the final position.

The movement path may be selected manually, automatically, or it may beselected by a user with computer assistance. Examples of methods,devices and systems for choosing a final position and/or a movement pathfor aligning a subjects teeth may be found in many of the patentapplications previously referred to and incorporated by reference,including U.S. patent application Ser. No. 11/013,145, titled“Fabricating a base compatible with physical dental tooth models” byHuafeng Wen, filed Dec. 14, 2004, U.S. patent application Ser. No.11/013,156, titled “Producing non-interfering tooth models on a base” byHuafeng Wen, filed Dec. 14, 2004.

For example, software may be used to assist the user in choosing a finalalignment of a subject's teeth. In one example, digital representationsfor the teeth are provided from a digital tooth arch model. A digitaltooth arch model is then utilized to provide visual feedback to the userwhen the position and/or orientation of one or more of the individualteeth within the tooth arch are modified. Individual physical models ofthe teeth within a subject's tooth arch may be used to represent thetooth arch.

In another variation, software running on a computer generates a userinterface to allow the user to display and modify one or more of theteeth within the tooth arch model. The position of individual teethwithin the tooth arch model may be electively modified (e.g., displaced,rotated, etc.) relative to the other teeth in the tooth arch model. Theuser interface may display the pre-modified tooth arch model and thepost-modified tooth arch model in a side-by-side manner. This displaypermits the user to verify the changes by comparing the modified archwith the original arch (starting arch). Three or more digital archesmodels of the same subject may be provided with various changes oradjustments to one or more of the teeth. The user interface may beconfigured to allow the user to select any two of the arch models anddisplay them side-by-side for comparison.

In some variations, once a target (or final) alignment positions for theteeth has been determined, the movement pathway may be determined. Themovement pathway may be calculated based on a number of parameters,including the total distance of tooth movement, the difficulty in movingthe teeth (e.g., based on the surrounding structures, the types andlocations of teeth being moved, etc) and other subject-specific datathat may be provided. Based on this sort of information, the softwaremay generate an appropriate number of intermediary steps (correspondingto a number of treatment steps, or aligners to be manufactured). In somevariations, the user may specify a number of steps/aligners, and thesoftware maps different aligner configurations accordingly.Alternatively, the movement pathway may be guided by (or set by) theuser.

In one example, a series of nine pairs of different tooth arches,representing projected teeth positions during the course of anorthodontic treatment plan, are generated by a computer after the userselects the final alignment position. The user may elect any of thetooth arches within the treatment plan and display them in aside-by-side manner. The user may be permitted to make changes to theteeth within the tooth arches. For example, one window may show thetooth arch with the teeth in the original untreated positions. A secondwindow may show the tooth arch with the teeth in their indented targetpositions. The user may modify the tooth arches in a window if desired.An aligner may then be created based on the modified tooth arch in thewindow based on the digital representations of the tooth arches atdifferent stages of the treatment.

Software may also be configured to allow the user to rotate the tootharch, such that the tooth arch can be examined from different views. Inone variation, the two set of arches in right and left windows arealways shown in the same directional view, such that if the user rotatesthe post-modified tooth arches in the right window, the correspondingpre-modified tooth arches will also rotate in the same direction and inthe same amount. If the pre-modified tooth arches in the left window isrotated by the user, the corresponding post-modified tooth arches willalso rotate in the same amount simultaneously. In one variation, acurser controlled by a computer controller (e.g., a computer mouse,touch pad, etc.) may be utilized to drag the digital representation ofthe tooth arch shown in the user interface to rotate the tooth arch.Optionally, icons representing selective predefined views of the tootharch may be provided within the user interface, such that the user canshow a desired view by selecting an icon. In one variation, by clickingon an icon, the tooth arches displayed in different windows will bechanged to show selected view of the tooth arches.

The computer software may simulate constraints to movement when bothselecting a final tooth conformation and when choosing a movementpathway. For example, the digital representation of the teeth maysimulate potential collision between the teeth as the positions of theteeth are modified by the user or through a computer program. Inaddition, boundary conditions may be predefined to limit the amount ofmovement of the tooth (e.g., root rotation). For example, rotation ofthe crown of a tooth may cause large displacement at the tip of theroot, which can cause the root to collide with the root of an adjacenttooth. In one variation, the computer software is configured to detectcollision when a boundary parameter representing a first root iscrossing over a boundary parameter representing a second root. Thesoftware may indicate to the user that collision has occurred or maysimply not allow a movement pathway in which collision will occur. Inanother variation, once collision has been detected, the software willnot allow the user to rotate the tooth further in the collisiondirection and may begin looking for a different movement pathway toachieve the same (or a similar) final alignment position. In anotherexample, each of the teeth (i.e., crown and/or root) is represented by amesh of points. When the mesh of points representing the first teeth andthe mesh of points representing the second teeth occupies the samespace, this would indicate that the two teeth have collided.

In another variation, boundary parameters may be defined to simulatephysiological conditions in the subject's mouth and jaw that would limitthe rotation and/or displacement of the tooth. In one example, thesoftware utilizes boundary parameters to prevent over-rotation of theteeth. For example, a boundary condition may be defined for each toothto limit the amount of the rotation and/or displacement that can beprescribed by the user. The boundary condition may be generated based onpopulation sample data of humans' teeth, gum, and jaw structures. Theboundary condition may then be utilized to prevent the user fromdirecting the rotation or displacement of the teeth to an unrealisticcondition. Furthermore, boundary conditions may be determined fordifferent population subgroups. For each subject, the boundary conditionfrom the appropriate population sub-group that matches the subject'sphysical parameters may be used to provide better estimation of thephysiological limitations. In some variations, the boundary conditionsmay be determined for each individual patent based on data supplied(e.g., from X-rays, the model, etc).

The practitioner (e.g., an orthodontist) may manually determine (e.g.,by entering into the computer) a movement pathway, or the computer maygenerate a suggested movement pathway. In either case, the user mayadjust the movement pathway either before making any aligners, or afterthe subject has begun wearing an aligner or series of aligners. Thisallows the orthodontist to correct the prescription if necessary.Furthermore, the user may provide comments or instructions that may beused when creating the movement pathway and/or the correspondingaligners. Thus, the orthodontist may modify his prescription for a newaligner by modifying one or more of the teeth in the digitalrepresentation of the tooth arch.

1. Constraints on Movement

As described above, movement of components of the model (e.g., theteeth) to formulate a movement pathway or a final alignment may beconstrained by various factors.

A tooth model may be described as having a tooth body and tooth roots.In general, the tooth movements can be decoupled into rotations aroundthe roots and translations of the roots. The translations of the rootsmay be described by a coordinate system, such as Cartesian coordinatesdefined by X-, Y-, and Z-axes. In one variation, movement of the toothroots may be though of as movement of the center of the tooth separatefrom the “orientation” of the tooth. The longitudinal axis, L, of atooth can rotate along a polar direction P, a direction of self-rotationS, and an azimuthal direction A. Movement in P, S and A may be thoughtof as orientation movements. Although alternative descriptions ofmovements exist, his definition of the tooth movement has the advantageof decoupling the large (rotational) orientation movements from small(translational) movements. Since the roots are generally anchored, theeasiest movements of a tooth 300 under external forces are the rotationsaround the roots, whereas the translations of the roots are of muchsmaller magnitudes. Thus, the rotation or orientation movements can beviewed as movements about a pivot point about which the tooth rotates.FIGS. 3A and 3B illustrate these axes of movement (X,Y,Z) and (P,S,A).

Thus, movements of the tooth model can be described by coordinatesystems identical to those used for the subject's tooth. For example,the roots of the teeth may be simulated by the registration features, asdescribed above. Translation of the registration features may bedescribed by a Cartesian coordinate system based on the X′-, Y′-, andZ′-axes, and rotation of the tooth model can be described by therotations of the longitudinal axis L′ of the tooth model along the polardirection P′, the self-rotation direction S′, and the azimuthaldirection A′.

In some variations, movement in one or more of these directions islimited or constrained. For example, when planning the movement pathway(or helping the user select a movement pathway) the software or physicalmodel may prevent certain types of movement (e.g., in constraineddirection) or may prefer alternative types of movement in order toachieve a final alignment of the teeth. In some variations, the softwaremay “weight” certain types of movement differently, e.g., correspondingto the difficulty in moving in one or more directions. These weights maybe used in calculating the movement pathways. In some variations, thesoftware may tell the user when a movement in a constrained directionhas been chosen, or the software may simply prevent the technician orpractitioner from selecting movement in that direction.

In some variations, because the registration features mimic the roots ofthe subject's teeth, the tooth models attached to the dental base canmost closely simulate the present or the target configurations of thesubject's teeth. The movements of the subject's teeth are decoupled tolarge movements (i.e., rotations around the registration features or theroots of the teeth) and small movements (i.e., translations of theregistration features or the roots). The dental aligner can therefore bedesigned to focus on the large movements at each treatment step, whichnormally involves minimal translation of the roots. Dental aligner canbe thus be formed using the tooth models generated at various pointsalong the movement pathway. Thus, a treatment series may be generatedhaving some number of positions (e.g., an initial or starting position,a first treatment position, a second treatment position, etc. untilachieving a final position).

In some variations, the practitioner may adjust the treatment positionswhile the subject is still undergoing treatment, either based on userpreference or based on feedback from the subject's treatment to date.

2. Feedback in Forming the Movement Pathway

As described above, a movement pathway may be adjusted during treatmentof a subject. For example, after selection of an alignment pathway, andconstruction of one or more aligners, additional subject data (e.g.,teeth measurements taken during treatment) may be used to refine oralter the movement pathway and therefore re-design the movement pathway,possibly including the final alignment position. In some variations, thepractitioner (e.g., an orthodontist) may refine the treatment pathway,including the final position, during treatment.

In some variations, the treatment path may be modified by measuring theactual position of the subject's teeth during the alignment procedure.For example, measurements of the subject's teeth may be taken by anyappropriate method, including the scanning methods previously described.In one version, a negative impression of the subject's teeth is taken atsome point during the treatment period, after the subject has worn analigner. Measurements taken from the subject's teeth may then becompared to the initial position, the final position, and any of theintermediate treatment positions. These measurements may then provideinformation that is feed back into the design of the next treatmentsteps.

In some variations, measurements taken during treatment may providesubject-specific information on how responsive a subject is to thetreatment and may allow further customizing of the treatment. Forexample, if a subject has worn a first aligner (corresponding to a firstalignment position) for a specified amount of time, the movement of theteeth from the original position to the first alignment position may bedetermined by comparing the actual position of the teeth after wearingthe first aligner to the initial and first alignment positions. Themovement path may then be modified to correct for differences betweenthe anticipated first alignment position and the actual first alignmentposition. In some cases, additional alignment steps may be added to themovement pathway, or the movement pathway may be changed to indicatepreviously unsuspected constraints on the movement of some or all of theteeth.

Described below are Examples of many of the different components of thedevices, methods and systems of alignment described herein. Any of thesteps described may be used in combination with any of the other steps,or parts of other steps.

EXAMPLES Example 1 Treatment Method with Feedback

FIG. 1A illustrates one method for providing orthodontic treatment for asubject using feedback. First, the initial configuration of thesubject's dental arch(s) is measured 110. The initial configurations ofthe subject's teeth can include the positions and the orientations ofthe subject's teeth before the treatment begins. The analysis of theinitial configuration of the subject's teeth can include making dentalimpressions of the subject's upper and/or lower arches. A digital modelof the subject's dental arches can then be produced. The surfacelocations of the dental impressions can be measured to determine thepositions and the orientations of the subject's teeth, as describedabove and in the incorporated references. For example, details ofconducting measurement on dental impressions are disclosed in the abovereferenced U.S. patent application Ser. No. 11/013,159, titled“Producing a base for accurately receiving dental tooth models” byHuafeng Wen, filed Dec. 14, 2004 and U.S. patent application Ser. No.11/013,157, titled “Producing accurate base for dental arch model” byHuafeng Wen, filed Dec. 14, 2004.

A practitioner may determine a target configuration for the subject'steeth. This target configuration may be a final target configuration 120(e.g., indicating a final configuration of the teeth at the end of thetreatment), or it may indicate an intermediate target configuration. Thepractitioner may indicate a target configuration by manipulating aphysical or digital model and providing the manipulated model, or byproviding verbal or written instructions on how the teeth should bepositioned with respect to their current position (or other reference),or some combination thereof.

The practitioner may design a treatment plan by determining a targetarrangement of the teeth 120 (e.g., a final target arrangement). Asmentioned above, a final target arrangement does not have to beexplicitly determined at the early stage; treatment can begin and thepractitioner can settle on the final arrangement only after seeing howthe subject's teeth respond to treatment. Once a target arrangement isdetermined, a movement path may be determined 130. The movement path isthe path taken by the teeth as they are moved by the aligner or alignersin order to achieve the target arrangement. The aligners typically movethe teeth incrementally. If the movement path requires that the teethmove more than a predetermined amount (e.g., 0.3 mm or less in X or Ytranslation), then the movement path may be divided up into multiplesteps, where each step corresponds to a separate target arrangement 140.The predetermined amount is generally the amount that an aligner canmove a tooth in a particular direction in the time required for eachtreatment step (e.g., 3 weeks). A dental aligner may be fabricated foreach of these treatment steps 150.

The movement path may be determined with the assistance of an analysisdevice such as a computer analysis device (e.g., a computer runninganalysis logic). For example, the analysis device may be configured toinclude constraint logic that indicates the constraints on the movementof the teeth, as described above. Thus, the movement path may beexplicitly indicated by the practitioner or may be suggested by theanalysis device and approved by the practitioner. In some variations,the movement pathway is generated by a technician with the assistance ofanalysis software (see Example 2, below). The computer analysis deviceis typically configured to store the initial and the targetconfigurations (e.g., final and intermediate target configurations) ofthe subject's teeth as well as the movement path(s) from the initialconfiguration to the target configuration. The movement path may avoidteeth collision and overlap and may also take into account movementconstraints for the teeth, including constraints on how much a tooth maymove during a given treatment step.

As mentioned, the movement paths may be divided into a plurality ofsuccessive treatment steps 140. There can be, for example, ten to fortysteps. One or more dental aligners can be fabricated for each treatmentstep 150. The subject wears one of the dental aligners to move his orher teeth as part of each step 160.

Dental aligners may be fabricated as described herein. One or aplurality of dental aligner can be provided to the subject at each stepof the dental treatment. Each of the aligners can be worn for a periodof time from a few hours, to a few weeks (e.g., 3 weeks). Aligners maybe worn continuously over for a portion of a day.

As described, orthodontic treatment methods may include “feedback”allowing the teeth to be iteratively adjusted during treatment based onhow the teeth have responded to one or more of the dental aligners.Thus, one or more aligners may be designed for future treatment stepsonly after analyzing the arrangement of the subject's dental arch afterthe subject has worn a dental aligner as part of the ongoing treatment.

The teeth movement caused by the dental aligner is normally not exactlythe same as designed by the treatment plan. Thus, as described above,the movement of the teeth may be analyzed after an aligner has been worn170 to determine their position, in the dental arch, or how much theyhave moved since beginning the previous treatment step (or steps). Themovement resulting may be factored into the treatment plan, particularlyin the design of additional aligners. The positions and orientations ofthe subject's teeth can be measured, which can serve as a feedback tothe adjustment of the treatment plan.

A negative impression of the subject's dental arch can be obtained afterthe subject has worn the dental aligner for a period of time, andmeasurements taken as described above for determining analyzing theconfiguration of the subject's dental arch. FIG. 2 illustrates onemethod for determining the configuration of a subject's dental arch. Asubject's negative dental impression 280 can be fixed in a container 290using an epoxy. The container 290 can be marked by one ore morereference marks 295 that can define the coordinates of the impression280. The relative positions of the subject's teeth are measured off theimpression using a mechanical location device 200. An example of amechanical location device is the Microscribe available from Immersionand Phantom. Microscribe is a hand-held 3D digitizer that can develop adigital computer model for an existing 3D object. The mechanicallocation device 200 can include mechanical arms 210, 220 having one ormore mechanical joints 230. The mechanical joint 230 is equipped withprecision bearings for smooth manipulation and internal digital opticalsensors for decoding the motion and rotation of the mechanical arms 210,220. The end segment is a stylus 240 that can be manipulated to touchpoints on the dental impression 280 held in the container 290. Themechanical location device 200 can be fixed to a common platform as thecontainer 290. Accurate 3D positional and angular information of thepoints that the stylus touches can be decoded and output at theelectronic output port 270. The positional and orientational informationcan be obtained by additional decoders. Additional sensors can be placedat the tip of the stylus to measure the hardness of the surface of themeasurement object. Immersion Corp.'s MicroScribe uses a pointed stylusattached to a CMM-type device to produce an accuracy of 0.009 inches.

In measuring the teeth positions from the impression of the subject'steeth, the MicroScribe digitizer is mounted on a fixture fixed to a baseplate. The device can communicate with a host computer via USB or serialport. A user (e.g., a technician or manufacturer) then selects points ofinterest at each tooth positions in the impression and places the stylusat the point of interest. Positional and angular information are decodedand then transmitted to the computer. The Cartesian XYZ coordinates ofthe acquired points are then calculated and logged for each firstfeature location and orientation (or alternatively each tooth).

A new coordinate system is established based on the container chamber inwhich the arch impression is held. This system is established by takingreadings for two points on two sides of the container to define thex-axis. Another reading on the plane establishes the x-y plane. Anorigin is then determined on the x-y plane. The z-axis will beestablished by taking the cross product of the x-axis and y-axis.

The user next selects a plurality of points on the surfaces of the archimpression corresponding to each tooth. The 3D points measured from theimpression surfaces are then interpolated to create surfaces and solidsintegrated into an overall design.

The number of points defining the curves and number of curves depends onthe desired resolution in the model. Surfacing functions offered by thedesign application are used to create and blend the model surfaces. Themodel may be shaded or rendered, defined as a solid or animateddepending on the designer's intentions. All the readings acquired by thestylus can be rendered in real time to allow the user to visualize thedigital tooth models. The coordinate axes and points can be rendered inthe software using different colored cylinders/spheres etc. so as todistinguish the different meanings of values.

The teeth positions can also be obtained by optically scanning thedental impression or tooth models molded using the dental impression. Anoptical scanning system can include a scan table on which the dentalimpression or the tooth models can be mounted. The scan table can berotated by a rotation mechanism under the control of a computer. One ormore image capture device can capture images of the dental impression ortooth models molded as the scan table is turned to an angular position.The optical axis of the image capture device can be for example 45degree off the vertical axis (or the top surface of the scan table).

A digital dental arch model can include a plurality of digital toothmodels. The digital dental model can be developed based on the firstfeature locations and orientations or alternatively the coordinates ofthe physical tooth models acquired by the mechanical location device.

The images of the dental impression or tooth models are analyzed. Thecoordinates of a plurality of surface points on the dental impression ortooth models are computed by triangulation using the captured imagedata. The surfaces of the dental impression or tooth models areconstructed by interpolating computed coordinates of the points on thesurface. The positions of the subject's teeth can thus be obtained. Thepositions of the subject's teeth can also be measured by a lasertracking system and a motion tracking system. Details of measuringlocation information on a dental impression of a subject are disclosedin the above referenced U.S. patent application Ser. No. 11/013,159,titled “Producing a base for accurately receiving dental tooth models”by Huafeng Wen, filed Dec. 14, 2004 and commonly assigned U.S. patentapplication Ser. No. 11/013,157, titled “Producing accurate base fordental arch model” by Huafeng Wen, filed Dec. 14, 2004.

The measured positions of the subject's teeth are compared to the targetconfigurations at the treatment step in the treatment plan in step 180.If the target configurations are achieved within a specified tolerance,the treatment can proceed according to the original design. One or morealigners can be produced for the next treatment step as originallyplanned in step 190.

If it is found that the dental aligner did not move the subject's teethto the desired target configurations in step 180, the orthodontist candesign another dental aligner in response to the measured current teethpositions and the desired positions for the subject's teeth at thisstage of the treatment. Typically, the orthodontist uses computersoftware to simulate the teeth movement to the target configurations forthe subject's teeth. The target configurations include desired teethpositions and orientations. The target configurations can be specifiedin the original treatment plan for this or the next step of thetreatment. Furthermore, the orthodontist can also dynamically adjust thetarget teeth configurations for the next treatment step in accordance tothe movement of the subject's teeth.

As described, dental aligners can be fabricated with the assistance ofphysical tooth models that can be assembled to form a physical dentalarch model. The physical dental arch model can be formed on a dentalbase. The physical tooth models of the subject's teeth can be fabricatedand used for one or more treatment steps. The dental base can include aplurality of receiving features for receiving the tooth models. Thetooth models can comprise registration features compatible with thereceiving features. The dental base can include different configurationseach corresponding to one or more treatment steps. Dental aligners canbe conveniently and inexpensively fabricated using the physical archmodels at different treatment steps. The shared use of physical toothmodels and the dental base between treatment steps significantly reducesthe treatment time and cost. Various steps of the disclosed treatmentsystem and methods are disclosed in the above referenced and commonlyassigned U.S. patent applications, the disclosures of which areincorporated herein by reference.

Physical tooth models can be fabricated before the first treatment stepor produced again in any of the subsequent steps if any of the toothmodels are worn or damaged. A plurality of tooth models can also befabricated at once to save set-up time and handling cost. In oneexample, the physical tooth models can be molded using the negativeimpression 280 in a casting chamber or the container 290. The container290 can be filled with a malleable casting material. The container 290can be sealed. The casting material is solidified with the assistance ofheating, pressure, and/or UV irradiation. A physical arch model of thesubject's arch can then be obtained by removing the solidified castingmaterial. The physical arch model can then be separated into a pluralityof tooth models. The one ore more reference marks 295 can besimultaneously molded on the physical arch model such that the surfacepoints on the physical arch model can be accurately translated back tothe original coordinates for the negative arch impression. Details ofmolding physical arch models are disclosed in the above referenced andcommonly assigned U.S. patent application Ser. No. 11/013,160, titled“System and methods for casting physical tooth model” by Huafeng Wen,filed Dec. 14, 2004 and U.S. patent application Ser. No. 10/979,823,titled “Method and apparatus for manufacturing and constructing aphysical dental arch model” by Huafeng Wen, filed Nov. 2, 2004, thedisclosures of which are incorporated herein by reference.

FIG. 3A illustrates a subject's tooth 300 that includes a tooth body 310and roots 320. In accordance with the present invention, the toothmovements can be decoupled into rotations around the roots 320 andtranslations of the roots 320. The translations of the roots 320 can bedescribed by a coordinate system, such as a Cartesian coordinate definedby X-, Y-, and Z-axes. The longitudinal axis L of the tooth 300 canrotate along the polar direction P, the direction of self-rotation S,and the azimuthal direction A. Although alternative descriptions ofmovements exist, the disclosed definition of the teeth movement has theadvantages of decoupling the large (rotational) movements from the small(translational) movements. Since the roots 320 are anchored down deep,the easiest movements of a tooth 300 under external forces are therotations around the roots 320, whereas the translations of the roots320 are of much smaller magnitudes. The roots of the tooth can be viewedas a pivot point about which the tooth rotates.

FIG. 3B illustrates a tooth model 350 that can simulate the movements ofthe subject's tooth 300 in FIG. 3A. The tooth model 350 can include atooth model body 360 and one or more registration features 370. Thetooth model body 360 can simulate the tooth body 310. In accordance withthe present invention, the registration features 370 can simulate theroots 320. The registration features 370 can include a pin, aprotrusion, a stud, a socket, a slot, a hole, and other features thatcan be attached to the receiving features on the dental base as shown inFIGS. 5 and 6.

The simulation of the registration features 370 of the roots 320 can beassisted by a digital representation of the subject's tooth, that is, adigital tooth model. Images of the subject's teeth including the rootscan be captured by X-ray in different directions. 3D digital models ofthe subject's teeth can be constructed from the images. The tooth modelcan also be scanned optically or measured by a location device to obtaina digital tooth model. The digital tooth model can be extrapolated todescribe the roots of the tooth. The registration features 370 can thenbe simulated such that the ends of the registration feature 370 are atthe same locations relative to the tooth model 350 as the roots 320relative to the tooth 300.

The movements of the tooth model 350 can be described by coordinatesystems identical to those used for the subject's tooth 300 in FIG. 3A.The translation of the registration features 370 is described by aCartesian coordinate system based on the X′-, Y′-, and Z′-axes. Therotation of the tooth model 350 can be described by the rotations of thelongitudinal axis L′ of the tooth model 350 along the polar directionP′, the self-rotation direction S′, and the azimuthal direction A′.

FIG. 3C shows a generalized tooth model 380, having a tooth body 380 andalignment pins (simulating roots) 390.

Dental aligner can be formed using the tooth models attached to thedental base at each step of the dental treatment. Because theregistration features mimic the roots of the subject's teeth, the toothmodels attached to the dental base can most closely simulate the presentor the target configurations of the subject's teeth. The movements ofthe subject's teeth are decoupled to large movements (i.e., rotationsaround the registration features or the roots of the teeth) and smallmovements (i.e., translations of the registration features or theroots). The dental aligner can therefore focus on the large movements ateach treatment step, which normally involves minimal translation of theroots. The dental aligner produced can therefore produce more accuratemovement in the subject's teeth.

The disclosed dental aligners can also be more effective in movingsubject's teeth. The prior art dental aligners often attempt to rotatethe subject's teeth around point above the roots of the teeth, whichoften creates un-realistic or unwanted movements. The undesirablemovements often have to be corrected in rework steps. The disclosedsystem can reduce the number corrective or rework treatment steps, thusminimizing the total number of treatment steps. The cost and time forthe treatment are reduced.

The disclosed system and methods also simplifies the orthodontictreatment process compared to the prior art systems. The decouplingbetween rotations around the roots of the subject's teeth and thetranslation of the roots helps to focus the teeth movements on theprimary movements, that is, the rotations around the roots of the teeth.In many cases, no or only minimal translational movements are requiredat the roots of the teeth.

As described above, constraining the movement of components of thedental arch (e.g., teeth) may also help in determining the intermediatedigital (or physical) models interpolated from the initial model and thefinal (desired) dental arch configuration. In particular, constrainingthe movement of the teeth so that they more accurately model themovement of teeth whose roots are embedded within the gingiva and jaw islikely to result in more accurate and effective aligner designs. One wayto achieve this is to constrain or limit movement in X-, Y- and/orZ-axes, while more readily allowing movement about the roots (e.g.,azimuth and polar movement).

In other cases, a tooth can be constrained to rotate along just one ortwo of the polar, self-rotation, and the azimuthal directions in aparticular treatment step. In other cases, the roots of a tooth can beconstrained not to move in the X-, Y- or Z-directions in anothertreatment step. The constraints on the rotational movements help toreduce the variable degrees of freedom adjusting teeth configurations,which simplifies treatment designs.

In one aspect, the constrained teeth movement reduces the probability ofinterference between neighboring teeth. Details of designing teethmovement without interference between adjacent teeth are disclosed inthe commonly assigned and above referenced U.S. patent application Ser.No. 11/013,156, titled “Producing non-interfering tooth models on abase” by Huafeng Wen, there content of which is incorporated herein byreference.

In another aspect, different constrained tooth movement at differenttreatment steps makes it easier to monitor the teeth movement over thetreatment process. The treatment can be more focused, and the teeth canbe moved more directly to the final configuration of the treatment plan.The simplified teeth movement also reduces the chance for incorrectmovement and thus reduces the corrective measures in the treatment. Thenumber of treatment steps can be reduced as a result, which decreasesthe cost and time spent.

The registration features 370 can be simultaneously produced in themolding process by molding them into the malleable casting materials.For examples, the registration features 370 can be pins that areinserted into the malleable casting material before it is solidified.Alternatively, the registration features 370 can be produced in thetooth model 350 after the making of the physical arch model and beforethe physical arch model is separated into tooth models 350. For example,the registration features 370 can include sockets that can be drilled bya drilling system 400 on the physical arch model as shown in FIG. 4.Details of obtaining a physical dental arch model having registrationfeatures and 3D reference positions are disclosed in above referenced USpatent application titled “Producing a base for accurately receivingdental tooth models” by Huafeng Wen, filed Dec. 14, 2004, the content ofwhich is incorporated herein by reference.

The tooth model 350 shown in FIG. 3B can include a tooth model body 360and one or more registration features 370. The registration features 370can include a pin, a protrusion, a stud, a socket, a slot, a hole, andother features that can be attached to the receiving features on thedental base as shown in FIGS. 5 and 6. The registration features can besimultaneously produced in the molding process by molding them into themalleable casting materials in step 185. For examples, registrationfeatures that are pins can be inserted into the casting material beforeit is solidified. Alternatively, the registration features 370 can beproduced in the tooth model 350 after the making of the physical archmodel and before the physical arch model is separated into tooth models350. For example, the registration features 370 can include sockets thatcan be drilled by a drilling system 400 on the physical arch model asshown in FIG. 4. Details of obtaining a physical dental arch modelhaving registration features and 3D reference positions are disclosed inabove referenced US patent application titled “Producing a base foraccurately receiving dental tooth models” by Huafeng Wen, filed Dec. 14,2004, the content of which is incorporated herein by reference.

Receiving features for receiving the registration features in the toothmodel are next produced on a dental base in step 186. The receivingfeatures on the dental base are complimentary to and compatible with theregistration features on the tooth models. The receiving features caninclude one or more of pins, protrusions, studs, sockets, slots, andholes. As shown in FIG. 4, the dental base 410 is held to a stage 415. Adrilling device 430 is mounted on a positioning system 440 that can movethe drilling device 430 in three dimensions. The positioning system 440first locates the reference points 412 on the dental base 410 under thecontrol of a computer 420. The reference points 412 precisely correspondto the reference marks 295 in the dental impression 280. The positioningsystem 440 can define a coordinate system based on the reference pointson the dental base 410. The coordinates of the dental base 410 can bequantitatively translated to the original coordinates of the negativedental impression 280 using the reference marks 295. The computer 420stores the locations of the sockets to be made on the dental base 410.The locations of the sockets correspond to the registration features 370(pins) on the tooth model 350. Both the sockets and the registrationfeatures 370 can be defined by the original reference marks 295. Forexample, the locations of the receiving features on the dental base candepend on at least two factors: first, the measured positions of thesubject's teeth after the teeth movement caused by the last dentalaligner; and second, the desired positions of the subject's teeth.

The positional system 440 moves the drilling device 430 to the intendedlocations for the sockets stored in the computer 420. Drilling device430 can drill the sockets using a mechanical drill bit or by burning toform them with any appropriate device, such as a high-power laser beam.

Alternatively, the dental base 410 rather than the drilling device 430can be mounted on a positioning device. The positioning device iscapable of producing relative movement between the dental base 410 andthe drilling device 430. A coordinate system is developed based on thereference points 412 that can be quantitatively translated to thecoordinate system based the reference marks 295 on the dental impression280. The dental base 410 is moved to positions to allow the sockets tobe drilled at the intended locations. The precise registration betweenthe teeth positions on the dental base 410 assures the tooth models 350accurately mounted on the dental base 410 as specified by the desiredpositions (or the target configurations) of the teeth for the nexttreatment step.

FIG. 5 is a top view of a dental base 500 comprising a plurality ofsockets 510 and 520 for receiving the studs of a plurality of toothmodels. The positions of the sockets 510,520 are determined by eitherthe initial teeth positions in a subject's arch or the teeth positionsduring the orthodontic treatment process. The base 500 can be in theform of a plate as shown in FIG. 5, comprising a plurality of pairs ofsockets 510,520. Each pair of sockets 510,520 is adapted to receive twopins associated with a physical tooth model. Each pair of socketsincludes a socket 510 on the inside of the tooth arch model and a socket520 on the outside of the tooth arch model.

FIG. 6 shows a tooth model 610 affixed with two pins 615. A dental base620 includes sockets 625 that can be in registration with the pins 615.The sockets 625 are adapted to receive the two pins 615 to allow thetooth model 610 to be assembled with the dental base 620. Since thesockets 625 and the pins 615 are fabricated based on the same coordinatesystem. They can be in precise registration to allow them to beassembled together. The tooth models 610 are assembled onto the dentalbase 620 to form a dental arch model in step 187.

A dental aligner can be conveniently fabricated using the dental archmodel in step 188. FIG. 7 illustrates an arrangement of fabricating adental aligner using a dental arch model. A sheet 710 of aligner-makingmaterial is attached to a sheet holder and then lifted up near a heatingelement. The sheet can be made of uniform distribution of a singlematerial or comprise multiple layers of different materials. After thealigner-making material is heated by a specified time, the sheet holderis pressed on the subject's dental arch model on the base plate. Avacuum pump removes air at the bottom of the base plate to cause thesoftened aligner making material to relax and fittingly form around thesurface the subject's dental arch model. This process of aligner makingis referred to as the vacuum forming.

The subject's dental arch model can include registration points 412 thatcan be copied onto the sheet 710 of aligner-making material duringvacuum forming. The copied registration marks 720 are formed on thealigner 750. A digital arch model captures the shape information of thesubject's tooth models and the information about the registration marks.The digital arch model can further specify the location of the featuresto be produced on the subject's teeth to receive the through holes thatcan allow the dental aligner to be snapped onto the subject's teeth.

An aligner obtained as described herein may be specifically designed tomove the subject's teeth at the current stage of the treatment processtoward the desired positions. The aligner is to be worn by the subjectin step 160. The process from step 160 to step 180 can be repeated.

The physical tooth models and the dental base can be shared betweendifferent treatment steps. Physical arch models can be configured andre-configured for different treatment steps. Dental aligners can beconveniently and inexpensively fabricated using the physical arch model.

Example 2 Manual Determination of Movement Path and Intermediate TargetConfigurations

In one variation, the method of producing removable orthodonticappliances (aligners) relies upon a technician to initially set theintermediate target configurations (treatment steps). The aligners aremade of clear plastic and are molded to fit snugly over a subject'steeth, as described above.

Overall, the treatment system includes a series of aligners, each ofwhich has a configuration that differs slightly from the untreatedposition of the subject's teeth. Each aligner exerts pressure upon thesubject's teeth, forcing the teeth to conform to the configuration ofthe aligner. When the subject's teeth have conformed to theconfiguration of a particular aligner, the subject moves on to a newaligner. In general, the treatment process is finished when thesubject's teeth have reached the configuration desired by the treatingclinician.

FIG. 1B illustrates the steps followed by one variation of thistreatment method. The manufacturing process begins with subjectinformation provided by practitioner 1010. This information is collectedby the practitioner, through his examination of a subject, and includesdental impressions of the subject's upper and lower teeth, a “wax bite”(i.e., an impression of the subject's teeth that the subject creates bybiting into a piece of wax), x-rays of the subject's teeth, photographsof the subject's face, and a prescription. The manufacturing entity usesthis information to manufacture the aligners customized for eachsubject.

A physical model of the subject's teeth is created from the providedinformation by the manufacturing entity 1020. The dental impressions andx-rays of the subject's teeth are used to create a physical model of thesubject's teeth. This creation of a physical model is accomplishedthrough the following steps. First, a technician reviews the dentalimpressions and x-rays to determine the orientation of each of thesubject's teeth. By looking at the dental impressions and x-rays, thetechnician is able to determine the z-axis of each tooth, i.e., thedirection in which the tooth points. This “z-axis” information is inputinto a three-dimensional digitizer. As described above, athree-dimensional digitizer is a spatial measuring tool used todetermine the x, y and z coordinates of points on the surface of anobject. In this case, the three-dimensional digitizer is used todetermine the x, y and z coordinates of points on the surface of thesubject's dental impressions. The “z-axis” information is typicallycalculated by using a 3D digitizer, (e.g., a MicroScribe) to obtainseveral coordinates on the crown. These coordinates are then used toestimate the positions of the roots of each individual tooth of thesubject.

Next, a computer numerical controlled (CNC) milling machine is used todrill a series of holes, which correspond to the estimated rootpositions, into a plastic plate, (base plate). Two holes are drilled foreach tooth and a pin is inserted into each hole. The length of each pinis greater than the depth of each hole, such that, once inserted, eachpin partially protrudes from the base plate. Two base plates arecreated-one for the subject's upper arch and one for the subject's lowerarch.

Modeling material is next poured into the subject's dental impressionsand the base plates are mated to the dental impressions so that thepins, protruding from the base plates, protrude into the liquid modelingmaterial. As the modeling material hardens, the pins become embedded inthe material, creating a model of the teeth with two pins protrudingfrom each tooth. The models of the teeth, including the pins, areremoved from the dental impressions and base plates. Finally, thesemodels are then separated, i.e., cut apart to create individual modelsof each of the subject's teeth.

A digital image of the subject's teeth (a digital model) is thenproduced to help guide the treatment formulation 1030. The models of thesubject's teeth, the estimated positions of the roots of the subject'steeth, and the practitioner's prescription are used to create a digitalimage of the prescribed position of the subject's teeth. This process isaccomplished through the following steps. First, the models of each ofthe subject's teeth are mounted onto another base plate, referred to asa “scanning plate,” one at a time (or in some variations, in a group).The scanning plate may be made of the same kind of material as the baseplate used in the modeling process described above but is given adifferent name to indicate that it is used at a different point in theprocess and for a different purpose.

The model of each tooth, once mounted onto the scanning plate, isscanned using a laser to obtain data representing its three-dimensionalgeometry. These data, combined with the estimated root positions and thepractitioner's prescription, are used to create a digital image of theprescribed position of the subject's teeth, i.e., an image of thesubject's teeth positioned in accordance with the practitioner'sprescription. This digital image is referred to as the “PrescriptionViewImage” or RxView. The PrescriptionView is a computer graphic imageencoded in a data format. The data contained in the PrescriptionViewImage is adequate to create a visual representation of the subject'steeth, however, by itself it may not be adequate to provide a basis forthe manufacture of physical aligners.

The PrescriptionView is typically an image of the entirety of thesubject's teeth, including the portion of the teeth below the gum line.The PrescriptionView of the portion of the teeth above the gum line iscreated using the data obtained from the laser scan of the model teeth.The PrescriptionView of the portion of the teeth below the gum line isan approximation based on the type of tooth represented--for example,the image of a molar is based on the shape of a molar and the image of abicuspid is based on the shape of a bicuspid. The PrescriptionView maybe provided to the practitioner via computer for approval. Thepractitioner examines the PrescriptionView using a computer programknown, allowing the practitioner to submit instructions and treatmentmodifications. Once the practitioner has viewed the PrescriptionView,the practitioner may either approve the PrescriptionView or modify thePrescriptionView.

After the practitioner determines that an acceptable PrescriptionViewhas been created, a technician (e.g., part of the manufacturing entity)begins producing the aligners individually, for shipment of two sets ata time. A “set” of aligners includes an aligner for the subject's topteeth and an aligner for the subject's bottom teeth, unless the subjectseeks treatment for his top or bottom teeth, exclusively, in which casehis “set” of aligners will consist of a single aligner.

The physical manufacture of the aligners may utilize a third computerprogram that uses the data obtained from the laser scan of theindividual model teeth and the estimated positions of the roots of thesubject's teeth to create a digital image of the current position of thesubject's teeth 1040. A technician then looks at this digital image and,using the software, manually adjusts the positions of the teeth to afirst-modified position 1050. The technician generally relies uponjudgment and experience to manually adjust the positions of the teethusing the software, so that the movement necessary to change theposition of a tooth from the current position to the first-modifiedposition can be achieved using a single aligner. In making thisadjustment, the technician may refer to the PrescriptionView as a visualguide only, much as a lab technician would look at a physical model ofteeth as a guide. Data from the PrescriptionView does not need to beused in modeling these intermediate treatment steps (intermediate targetconfigurations of the teeth). In some variations, the software used tomodel these intermediate target configurations may apply the constraintsto the technician's ability to move the teeth. For example, thetechnician may be limited in how far he or she can move a tooth inrotation about the roots, or translate the teeth in x-, y- orz-directions, as described above. The software used by the technician tomodel the intermediate target configurations may also protect againsttechnician error by limiting the range of movement allowed each tooth.For example, it may prohibit the technician from positioning the teethin undesirable or impossible orientations, e.g., overlappingorientations.

Once this adjustment is complete, a dental aligner is manufactured fromthe first intermediate target configuration (the “first modifiedposition” described above) 1060. A computer numerical controlled (CNC)milling machine is used to drill a series of holes, corresponding to the“first-modified” root positions, into a base plate referred to as a“staging plate.” The staging plate is identical to the casting andscanning plates described above but is given a different name toindicate that it is used at a different point in the process. Thetechnician inserts each physical tooth model into its corresponding pairof holes in the “first-modified” staging plate. This creates a physicalmodel of the first-modified target position of the subject's teeth. Thetechnician then creates an aligner by thermoforming a polymer shell overthis physical model.

In some variations, a second-modified target position (e.g., a secondintermediate target configuration) may be generated immediately fromwhich a second aligner may be produced. The technician looks at thedigital image of the first-modified position with the software and,using his judgment and experience, manually adjusts the first-modifiedposition to a second-modified position, as described above. A computernumerical controlled (CNC) milling machine is then used to drill aseries of holes, corresponding to the “second-modified” target rootpositions, into a staging plate. The technician inserts the model teethinto the new staging plate holes, and a second aligner is molded overthe physical model.

Typically two aligners may be fabricated at a time, spanning six weeksof treatment, and provided to the subject direction, or to thepractitioner to provide to the subject to be worn 1070. These alignersmay be worn, for example, for 21 days. Two sets of aligners are sent toa practitioner at one time. The time during which the subject wearsthese two sets of aligners, 42 days (about 6 weeks) is referred to asthe “treatment period.” After two sets of aligners are provided to thepractitioner, the practitioner receives a message inquiring whether thepractitioner would like to make adjustments to the treatment, consultwith technician, or have the technician design and manufacture two morealigners.

As the stages of treatment progress, the practitioner may view the newlymodified teeth positions and provides feedback and input to thetechnician, changing the treatment pathway (e.g., the course of thetreatment) as the subject progresses from aligner to aligner. Subsequentaligners can be created by repeating this process, with continuingpractitioner input and modification as treatment progresses.

The practitioner has the ability to make adjustments to the next twosets of aligners for approximately four weeks after the start of eachtreatment period (leaving two weeks during which the next two sets ofaligners can be manufactured). This interactive process ensures thateach pair of aligners can provide repositioning based on the currentstate of the subject's teeth, as examined by the clinician.

As described herein, the actual movement of the dental arch (teeth) maybe feed back into the treatment. For example, the position of the teethafter the subject has worn one or more aligners may be used to plan thenext (or next few) treatment steps. In some variations, the practitionerprovides information about the configuration of the subject's teethafter the subject has worn one or more dental aligners to the technician(manufacturer) 1080. The manufacturer (or the practitioner) maydetermine the change in position for individual teeth 1090 and mayadjust the next target configuration accordingly 1050. If one or moreteeth is proving particularly resistant to movement, the practitionermay increase the amount of force applied to that tooth by the nextaligner(s) or may change the way that the tooth is being moved by thealigner. In some variations, the actual position of the subject's teethafter wearing the most recent aligner can serve as the actual startingpoint for determining the next target configuration, rather than usingthe previously determined intended target configuration, as describedabove.

In this example, the aligners are shipped to the practitioner two setsat a time, with the packaging being designed to allow the clinician toselect the proper set to give the subject without the necessity ofplacing marks or instructions on the aligners. For example, each set ispackaged individually and the packages are stacked one on top of theother, such that the top set must be removed first, leaving the bottomset intact and attached to the package, to be used during the secondhalf of the treatment period. The manufacturer can continue to fabricateand deliver aligners until the practitioner informs them that treatmentis complete.

In some variations of the aligners, buttons may be used in conjunctionwith the treatment. Buttons are small structures that are physicallybonded to a subject's teeth. Aligners can be manufactured such that theyinclude “windows,” i.e., holes through which these buttons protrude.When aligners with windows are fitted onto teeth with buttons, thealigners can exert additional or different forces upon selected teethallowing for more aggressive or more specialized tooth movement. Thepractitioner may indicate whether the subject requires buttons and, ifso, the prescription indicates where the buttons should be positioned.Based upon this prescription, the manufacturer creates a template, whichthe practitioner uses to attach, i.e., glue, the buttons to thesubject's teeth.

Thus, in the example provided above, the intermediate target positionsof a subject's teeth are determined using a technician's judgment andexperience and are not determined by any mathematical algorithm orformula. However, it should be clear that in forming the intermediatetarget positions, the technician may be guided or assisted by softwarewhich assists in both modeling the movement of teeth (e.g., reflectingrealistic interaction between teeth and difficulty to move in certaindirections, etc.).

Although specific embodiments of the present invention have beenillustrated in the accompanying drawings and described in the foregoingdetailed description, it will be understood that the invention is notlimited to the particular embodiments described herein, but is capableof numerous rearrangements, modifications, and substitutions withoutdeparting from the scope of the invention. The following claims areintended to encompass all such modifications.

All of the references provided herein are incorporated by reference intheir entirety for all reasonable purposes, and their disclosures areintended to be considered part of the full disclosure.

Although specific embodiments of the present invention have beenillustrated in the accompanying drawings and described in the foregoingdetailed description, it will be understood that the invention is notlimited to the particular embodiments described herein, but is capableof numerous rearrangements, modifications, and substitutions withoutdeparting from the scope of the invention. The following claims areintended to encompass all such modifications.

1. A method for providing orthodontic treatment, the method comprising:receiving an initial representation of the patent's dentition in aninitial arrangement; generating a treatment plan comprising a pluralityof successive treatment steps, wherein the plurality of successivetreatment steps incrementally reposition at least one of the patient'steeth from the initial arrangement towards a target arrangement;fabricating a first dental aligner based on the treatment plan, whereinthe first dental aligner corresponds to one of the plurality ofsuccessive treatment steps; monitoring treatment progress to determinewhether the patient's dentition is progressing along the plurality ofsuccessive treatment steps; generating a revised treatment plan based ona determination that treatment progress has progress off-track;fabricating a second dental aligner based on the revised treatment plan,wherein the second dental aligner corresponds to one of a plurality ofsuccessive treatment steps in the revised treatment plan.
 2. The methodof claim 1, wherein fabricating the first dental aligner comprisesthermoforming a polymer shell over a physical dental model.
 3. Themethod of claim 2, further comprising assembling the physical dentalmodel by inserting a plurality of tooth models into a dental base. 4.The method of claim 2, wherein the physical dental model correspondswith a patient's dentition at the one of the plurality of successivetreatment steps.
 5. The method of claim 1, wherein fabricating the firstdental aligner comprises using stereolithography to build a geometry ofthe first dental aligner layer by layer.
 6. The method of claim 1,wherein the initial representation comprises a three-dimensional modelcollected from an intraoral scanner.
 7. The method of claim 1, whereinmonitoring treatment progress comprises receiving an intermediaterepresentation of the patient's dentition; wherein the intermediaterepresentation is collected subsequent to the initial representation. 8.The method of claim 1, wherein monitoring treatment progress comprisesreceiving feedback from a dental clinician.
 9. The method of claim 8,wherein generating the revised treatment plan is based at least in parton the feedback from the dental clinician.
 10. The method of claim 1,wherein monitoring treatment progress comprises taking a dental cast ofthe patient's dentition.
 11. The method of claim 1, wherein monitoringtreatment progress comprises assessing treatment progress at a pluralityof points in time throughout treatment.
 12. The method of claim 1,further comprising providing the revised treatment plan to a dentalclinician for approval prior to fabricating the second dental aligner.13. The method of claim 12, wherein providing the revised treatment planto a dental clinician comprises providing a three-dimensionalrepresentation of the patient's dentition for display on an electronicdevice.
 14. The method of claim 13, wherein the three-dimensionalrepresentation is configured to be rotatable via user input.
 15. Themethod of claim 1, wherein generating the revised treatment plan isbased at least in part on information regarding individual patientresponse to treatment.
 16. The method of claim 1, wherein generating thetreatment plan comprises accounting for tooth movement constraints. 17.The method of claim 16, wherein the tooth movement constraints comprisesno movement to a tooth of the patient's dentition.
 18. The method ofclaim 16, wherein the tooth movement constraints comprises limitationsin a direction of one or more degrees of freedom to a tooth of thepatient's dentition.
 19. The method of claim 16, wherein generating therevised treatment plan comprises accounting for the tooth movementconstraints.
 20. A non-transitory computing device readable mediumstoring instructions executable by a processor to cause a computingdevice to perform a method, the method comprising: receiving an initialrepresentation of the patient's dentition in an initial arrangement;generating a treatment plan comprising a plurality of successivetreatment steps, wherein the plurality of successive treatment stepsincrementally reposition at least one of the patient's teeth from theinitial arrangement towards a target arrangement; fabricating a firstdental aligner based on the treatment plan, wherein the first dentalaligner corresponds to one of the plurality of successive treatmentsteps; monitoring treatment progress to determine whether the patient'sdentition is progressing along the plurality of successive treatmentsteps; generating a revised treatment plan based on a determination thattreatment progress has progress off-track; fabricating a second dentalaligner based on the revised treatment plan, wherein the second dentalaligner corresponds to one of a plurality of successive treatment stepsin the revised treatment plan.